Essay questions
Problem solving and
decision making
1. INTRODUCTION TO PHYSICS
Characteristics of instrument to measure diameter of ball bearing
Consistency is higher The reading is more consistent
Accuracy is higher Can give measurement closer to actual value Sensitivity is higher Can detect small
changes in value to be measured
Has no zero error To increase accuracy of reading. Every
measurement must be minus with zero error Has no parallax error Eye must be
perpendicular to the scale to avoid parallax error
2. FORCES AND MOTION
Method to reduce the impact of impulsive force in egg’s drop competition from a height. (Mk) The egg’s casing
made from soft material
Lengthen the time of impact
Use parachute To slow down the egg drop The egg’s casing
part that hit the ground when landing made from easy to crumple material
Absorb the impact// lengthen the time of impact.
Characteristics of student to be in a basket ball team. (Phg)
Mass is smaller More agile/ can change direction/increase speed easily
Taller Easy to shoot goal
Responding time fast Easy to catch ball Powerful More energy/not tired
easily
Faster Can
block/attack/run/defence faster
Suitable characteristics of rope used for parachute. (Pls)
Use a dynamic rope It is softer and could prevent injury. A lower density It is lighter Higher snapping
force
Not easy to snap A rope with smaller
diameter
It will occupy less space.
Suggestion to design a water rocket. Made from tougher
material
Not easy to break Aerodynamic/streamline
shape
Reduce air friction Angle of launching is The rocket can travel
45o very far
Amount of water is 1/3 of the whole volume
To increase momentum and impulsive force Attached fins to the tail
of the rocket
Rocket can move smoothly and stable Characteristics of the spring cradle
Low spring constant Less stiffer and the spring can oscillate with low frequency
Low density Small mass and lighter Low rusting rate Not easy to rust and lasts
longer. Two springs are
arrange in parallel
Can withstand a heavier baby
Put string in the spring
To prevent the baby from falling down in case if the spring breaks
Explain safety features of the car.
Safety belts. To prevent the passengers from being thrown forward due to the inertia when accident occurs. Air bags Cushion the passengers
from direct impact with the steering when accident occurs to reduce the impulsive force. Easy crumpled
steering.
To reduce impulsive force. Front and rear
crumple zone.
To extend time of impact so that the impulsive force will be reduced.
Use stronger spring for the suspension system
To reduce vibration when the car being used off road Anti-scattering
windscreen
Will not harm the passengers and driver when it breaks. Head rest To keep the position of
head when the car being hit from back.
Passenger safety steel cage/cell built from reinforced steel
To prevent the car from being crumpled when it is overturned.
Way so that the pole vaulter can jump higher and lands safer.
Run faster Increase the kinetic energy Use elastic pole Produce higher elastic
potential energy Use tight sport wear Reduce air friction Use thick mattress
with soft surface
Increase the interval of impact on landing, thus reduce the resultant impulsive force
Landing on the back Increase the surface area and reduce pressure Use a spike To run faster and increase
kinetic energy Modify a normal car into a racing car. Use of higher power
engine
To produce high thrust force
Use of strong composite material
Will not break/damage easily
Use of engine which is able to withstand high temperature
Will not damage at high temperature
Use of low density material
Aerodynamic shaped To reduce air resistance Use of spoilers at
front, rear and side of the car
To create a downward pressure (Bernoulli’s effect) to prevent the car from being lifted upward at high velocity
Use of wider tires To produce better grip to the road
Use of hydraulic brakes
So that the car can be stopped faster Center of gravity of
the car is lower
To increase the stability of car
Additional safety belt To prevent the driver being thrown forward during collision.
Improve the safety steel cage/cell with more reinforced steel
To prevent the car from being crumpled when it is overturned.
Method so the pole vault athlete can jump higher and safer.
Bend the body when running to take off.
To reduce the air friction so that the acceleration will be greater.
Wear tight clothes To reduce air resistance Use spiked shoes To give stronger grip for
greater speeding Pole is made from
soft but stiff material
The potential elastic energy is high thus the height of jumping can be increased
Pole is made from tougher material
Will not break easily Put soft and thick
mattress on the landing pit
To increase the time of impact and reduce the impulsive force
Land on the back Increase the surface area and decreases the pressure inverted. Design of the water rocket so that it can fly further and faster.
High volume / mass of water
Can increase the momentum to the back thus increase the explosive force
Soft drink bottle Decrease the mass and increase the explosive force
Add wing on the bottle
Rocket fly in stable Add something to
the part of the bottle to make it sharp and aerodynamic
Reduce the air resistance
Add weight to the head of the rocket
Rocket can move straightly and the head move 1st
Use a higher power pump
Pushing force to the back is high, momentum to the back is high
Flying degree is 45 degree
The flying distance is longer
Modify the ordinary motorcycle to become a racing motorcycle
Use softer and wider tires
To strengthen the grip of the tires on the road Use an aerodynamic
shape
To reduce the air resistance
Low center of gravity To make it more stable Made from low
density materials
More lighter and can increase the acceleration.
Use heavy engine and place it in the middle of the motorcycle
The motorcycle is more stable
Use powerful engine To produce high thrust force.
Use front and rear disc brakes
So that the motorcycle can be stopped easily. Design of the safety belts
Wider Large surface area will
reduce pressure to the driver/passenger
Can be expanded To reduce impulsive force Made from tougher
material
Does not break easily Made from non-stiff
material
So it is soft and comfortable to use Design of the satellite that falling back to the earth so that it is not damage.
Made from material that has higher specific heat capacity
Not easily become hot.
Aerodynamic shape To reduce air resistance Protected by a good
heat insulator
To prevent the heat reach/enter the inner part of the satellite
Made from low density material
The mass will be smaller so the impulsive force is reduced
Made from tougher material
Not break easily Attached with
parachutes
To reduce the velocity Attached with
cooling system
So that the satelite is not become hot/melt easily Design of springs for athlete’s exercise purposes Parallel arrangement To increase the stiffness of
the spring.
Short in length To reduce the extension of the spring.
Small in diameter Greater force is required to stretch the springs. Covered with plastic. Will not harm the athlete if
the springs are broken. Made from
non-rusting materials.
Can be used for a longer time/durable.
Fix with holder at the end of the spring
Can be easily be held and stretched
Fix an elastic rope in the springs
To prevent the springs from being stretched over it’s elasticity limit. Modification to the bus to improve the safety of the passengers.
Attach safety belts. To prevent the passengers from being thrown forward due to the inertia when accident occurs. Air bags Cushion the passengers
from direct impact with the front seat when accident occurs to reduce the impulsive force. Front and rear
crumple zone.
To extend time of impact so that the impulsive force will be reduced.
Use stronger spring for the suspension
To reduce vibration when the car being used off road
system Shatter proof windscreen and window panels
Break into small pieces with blunt edges and will not harm the passengers. Head rest To keep the position of
head when the car being hit from back.
Passenger safety steel cage/cell built from reinforced steel
To prevent the bus from being crumpled/collapsed when it is overturned. The bus is made
from tougher material
To avoid the bus being dented when involved in accident
Characteristic of spring to be used as a spring cradle. (Ktn)
Springs are arranged in parallel
Can support higher load. Use stiffer spring Not easily broken/ spring
constant is higher. Stainless steel Can be used for longer
time.
Shorter spring Spring constant is higher/stiffer.
Characteristics of arm exercise equipment made from spring that is suitable to use (J)
Spring made from stainless steel
Can be used for longer time.
Made from steel The spring is stiffer Spring made from
thicker wire
Wire not break easily Spring with smaller
diameter
Can withstand bigger force, more stiffer Modification of a fisherman boat so it can be used for deep-sea fishing. (MRSM)
Shape of the boat is streamlined
Less water friction. Made from tougher
material
Can withstand big wave Stainless steel Can be used for longer
time. Less maintenance Use ultrasonic wave More energy and can
penetrate deeper in the sea Bigger cool room Can put a large amount of
fish for longer time. Suitable characteristics of tractor used to do heavy works
Use larger tires Larger contact area produces low pressure and the tractor will not sink into the ground
Larger mass Larger inertia Low centre of gravity More stability Use liquid in the
hydraulic system
Liquid cannot be compressed Characteristics of spring to be used as the motorcycle spring
Smaller diameter of spring
Enough space to place the spring to the motorcycle. Higher elastic limit Can support more load Higher spring
constant
Small compression of the spring due to bigger load Smaller natural
frequency
Essay questions
Problem solving and
decision making
3. FORCES AND PRESSURE
Specification of watercraft/ship. Cross sectional –
Front side narrow and pointed
Reduce water resistance.
Hull made from aluminum
Lighter, stronger and not corrode.
Hydrodynamic shape. (Stream-lined)
Withstand shock waves. Reduce water resistance Diesel engine Cheaper and powerful Specification of submarine. (MRSM)
Use nuclear energy Can be used for longer time
Use ballast tank Can float and submerge easily
Fix with periscope Can look at the surface of the sea without floating on the surface
Use ultrasonic wave for radar
Can penetrate further
Characteristic of ship that can carry heavy loads. (SBP)
Streamlined shape Reduce water resistance Made from high
strength metal
Able to withstand bigger wave
Ship base cross sectional is wider
Abele to displace out more water to gain more buoyant force
Volume of the air space in ship is bigger
Can displace out more water//increase the volume so overall density is lower than water
Characteristics of hydraulic brake. has a high specific
heat capacity
Plate not easily heat up High boiling point Not easily boil at high
temperature
Fluid that Pressure can be transfer uniformly to whole the fluid Use non-corrosive
fluid
To not destroy the brake system
Brake made up of stainless steel
Not easily get rust
Design of a buoy on the sea surface Painted with bright
color
Can be easily seen in the morning and at night Fix lamps on the
buoy
Can be easily spotted at night
Made of thick and hollow material
Will not easily split and waterlogged
Fix small flags on the buoy
Can be easily split and waterlogged
Tied with ropes to the seabed
To prevent the float from sweeping away
Not made from metal To prevent the float from rusting and can be used for a long time.
Hollow and big in size
To have buoyancy and floats
Modification of a pesticide sprayer into painter sprayer.
Use a compressor with high ac voltage.
Provide high air pressure continuously.
Use compressor which produce high pressure.
To give high air pressure and produce stronger spray.
Made from low density materials
Light and can be bring to anyway
Use materials that resist to
corrosion/rusting.
Do not rust/corrode easily and last longer.
Use stronger materials
Do not easily broken or damaged
Use a bigger paint container.
Enable to store more paint. Adjustable nozzle
sprayer.
Can control the size of the spray.
Use longer nozzle spray.
Can spray the hidden part.
Design for the water tank to store a large amount of water
Made from
composite materials and fiber
Makes the tank stronger and does not break easily Made from low
density materials
More lighter Thick wall at the
bottom of the tank
To enable the water tank to withstand the large water pressure at the base of the tank
The water tank is placed on the thick concrete floor
So that the tank will not sink into the ground Large tank base To reduce pressure and
prevent the tank from sinking into the ground Build the water tank
at higher placed/ build a tall design
To increase the pressure of the water
Build larger water tank
Can stored more water
Modification to the hydraulic jack to enable it to lift mass of greater quantity
Use piston of bigger cross-sectional area
Can support greater force (weight)
Use low density material
Very light and easy to carry Non-compressible
liquid
Piston can be lifted up Longer handle Less effort needed to press
the small piston. Apply released valve
between small and main reservoir.
Liquid can flows into small reservoir.
Use stronger metal Not easily broken. Use non-corrosive
liquid
Will not corrode metal and long lasting.
Characteristic of an automatic tennis ball shooter. Small spring
diameter
To ensure that the elastic potential energy is higher. Thicker spring wires So that spring constant is
higher/more elastic/ball can be shot out at a high velocity.
More number of spring coils
So that the compression length is longer. Low density of tennis
ball is used
To ensure that it moves faster and further.
Suitable characteristics of a wings to be installed with the body of the aircraft
A shape of cross-section which is upper side is longer than the bottom
To produce the speed of air flow above the wings to be higher than the bottom area.
The area of the wing is larger
To produce larger lift force Made from low
density material.
Less weight//very light// to produce more upward resultant force. The difference in
speed of air is higher
To produce higher difference in pressure Design of the astronaut’s suit
White color/shinning To reflect the cosmic ray Made from tougher
material
Not easily torn Made from non-stiff
material
So that the astronaut can move easily.
Lined with lead/plumbum
To avoid the penetration of radioactive radiation. Use photographic
badge.
To check the exposure to the radioactive radiation of the astronaut.
Put on safety space helmet made from tough glass
To allow the astronaut to look at his surroundings.
Modification of hydraulic jet to overcome bigger force
Increase the surface area of bigger cylinder
Can easily push up bigger mass object
Decrease the smaller surface area of the cylinder
Can push up bigger mass with lesser force
Hydraulic oil that will not evaporate easily
Not easily evaporated when in high temperature Larger base area of
hydraulic jet
More stable Made from harder
alloy
Not easily break when supporting bigger mass object
Made from low rusting effect object
Can use for longer period
Way to increase the cleaning efficiency of cloth. Use detergent Remove the dirt and
moistening the cloth Use hot water Decrease the surface
tension of the water and moistening the cloth. Use automatic
mashing machine
Can control the amount of water being used
Use pipe water (soft water) not well water (hard water)
Enable the soap to form scum and increase the cleaning efficiency Clothes are made
from materials that can decrease the stickness between the clothes and the dirt
To avoid the oil and dust stick on the clothes
Waterproof clothing So that the clothes will not become wet when we sweat
Use more efficient washing machine
Clothes will be shivered along with the detergents to remove the dirt Use computerized
washing machine
Can control the usage/volume of water
Suitable characteristic of hydrometer to measure the density of concentrated acids.
Material made from glass
Glass does not corrode with acid
Small diameter of capillary tube
To increase the sensitivity of the hydrometer High density of shots Makes the hydrometer
stays upright Big diameter of
bottom bulb
To obtaine bigger upthrust force so the hydrometer can float
Suitable characteristics of metal to be used to built a boat
Streamlined (larus) in shape
To reduce water resistance Lower density
material
It will be lighter. Higher specific heat
capacity
Absorbs more heat but become hot slowly High strength Not easy to damage Corrosion effect is
lower
Not easy to rust/corrode.
Modification of the balloon so that the balloon can float and carry more passenger and has safety features for the passenger
Use hot air/
helium/hydrogen gas
Less dense than the atmosphere//lighter Larger basket Can bring more
passengers Balloon/basket made
from low density material
To reduce it weight
Basket fit with cushion
Comfortable and reduce impulsive force when landing
Use burner To control the height of the balloon by producing hot air.
Equipped with parachute
Can be used to save the passengers if the balloon is not functional. Equipped with safety
belts
To avoid passengers from fall down.
Suggestion to built a barge (tongkang) that can carry heavy load, faster and safer
Built from stronger material
Can withstand great force Lower density
material
Lightweight Has two stage
plimsoll line
Save in fresh and salt water
Bigger size Can place more load Streamlined-
aerodynamic shape
Reduce water friction
Specification of component in the brake system Disc brake is made
from higher specific heat capacity material
Not easy to become hot
Higher melting point of brake disc
Not easy to melt at high temperature Compression of brake liquid Difficult. Higher hardness of brake disc
Can be used for longer time.
Characteristics of fluid/liquid used as a hydraulic fluid
Higher boiling point Not easy to boil at high temperature
Higher specific heat capacity
Not easy to become hot Lower density So the hydraulic jack will
not become too heavy Has lower rate of
expansion
No easy to expand so the volume will be constant Design of hydrometer use to measure the density of an acid solution.
Smaller and longer stem.
Increase the sensitivity where the scale divisions are far apart so that small changes in density can be detected.
Use glass to built the hydrometer
Do not erode and small adhesive force. Larger diameter of
bulb
Higher up thrust force/displaces more liquid/able to float easily Use lead shot in the
bulb
Hydrometer can float vertically and stable. Suitable characteristic of hot air balloon which is able to carry more passengers to a higher altitude in shorter time.
Larger balloon size To produce bigger bouyant force.
Use many burners To produce bigger flame. Heat up the gas in shorter time.
Use synthetic nylon Lighter, strong and air-proof
Higher temperature of air in the balloon
Reduce the density of the air in the ballon.
Essay questions
Problem solving and
decision making
4. HEAT
Characteristics of an ice cream container. Use low specific heat
capacity to bulit inner box.
Easy to get cold//become cool easily.
Smaller size of ice cream box
Easy to carry because it is lighter.//Easy to become cool.
Outer box is made from PVC plastics
It is poor conductor// It is a good heat insulator. Outer box colour is
brighter.
Does not absorb heat from surrounding quickly. Has gap between
inner box and outer box and fill with heat insulator.
Avoid heat from
surrounding enter the inner box.
Suggest the suitability of material used to determine the specific heat capacity of aluminum Put on asbestos A good heat insulator.
Avoid heat loss by conduction. Wrapped with tissue
paper
Avoid heat loss by radiation/ to the surrounding Put some oil in the
hole
Better heat contact between aluminum block and thermometer. Higher power
immersion heater
Can increase the temperature faster. Characteristic of spatula use as a kitchen utensil (Mk)
Shape of the handle is slim
Easy to handle Density is lower Its is lighter
Higher melting point Not easily melt at higher temperature.
Higher specific heat capacity
Not easily become hot.
Desing of the ice container.
Lower density Smaller mass, lighter and easy to carry.
Higher specific heat capacity
The container is not easy to become hot/cold Made from good heat
insulator
To avoid heat from surrounding enter the container.
Shining surface. To reflect the heat from surrounding and avoid the heat being absorbed by the container.
Put a cover to the container.
To avoid heat from enter the container.
Design of the car radiator Use water as a
cooling agent
Higher specific heat capacity
Use bigger fan Can sucked out more heat from the radiator
Use water pump To help in the flow of water to the radiator
Paint the radiator with black paint
Black body can radiate more heat
Number of cooling fin is greater
Cooling will be more efficient
Characteristic of a school’s physics laboratory thermometer. (MRSM)
Bulb is smaller More sensitive
Rod is thicker Stronger, not easily break. Wall of the bulb is
thinner
Allow good heat conduction Capillary tube bore is
smaller
More sensitive, more accurate reading Use mercury Opaque and can be seen
easily
Do not stick the glass Rod is longer Wider range of scale and
more sensitive Suitable characteristics of the solar cooker Use concave mirror Will converges all light to
the focal point Use spherical
concave mirror
Will converges more light to the focal point hence increases the intensity of light/heat
Kettle is made from metal
Metal is good conductor. The kettle holder is
made from insulator
Easy to handle the kettle and not so hot
Modify/design of an efficient solar water-heating system.
Use insulator behind the absorber panel
To prevent the loss of heat energy
Use an absorber panel which is painted black.
A black surface is a good absorber of radiation so it will
absorb heat faster The pipe inside the
plate must be made of metal
Metal is a good heat conductor,
so it will transmit heat to water easily
Pipe embedded in plate must be long
Longer pipe will enlarge surface area will absorbs heat
faster Use glass cover on
the top of the panel
To trap heat energy. (energy is radiated in, but cannot radiate out again).
Design of the oven so that the oven will use less electricity and user friendly
Fix a bulb in the oven Can see the cake clearly Has stand so the
oven is at eye level
So the user can load and unload the cake easily. Built the oven so that
the oven has many racks
Can bake large amount of cake in one time. Insulate the oven
with good heat insulator
The heats will not loss to the surroundings.
Fit with a glass window to the cover.
Can see the cake without opening the cover. Fit a fan in the oven So the heat will spread
uniformly in the oven. Made from stainless
steel
Last longer/durable.
Design of the hot food container.
Lower density Smaller mass, lighter and easy to carry
Higher melting point Not melt easily at high temperature
Higher specific heat capacity
Not become hot easily Lower heat
conductivity
To avoid loss of heat to the surrounding.
Design of a cooking pot Pot made from lower specific heat capacity material
Easy to become hot with small amount of heat. Lower rate of
corrosion.
Not easy to corrode and does not contaminate the food
Made from lower density material
The mass will be lower and easy to handle
Made from aluminum Lower density and cheaper.
Handle is made from higher specific heat capacity.
Not easy to become hot.
Characteristics of hot water tank. High specific
heat capacity
- To ensure that it will not heat up fast.
Low density - So that its mass is smaller and easier to be managed. Low rate of
oxidation
- So that it will not be easily oxidized / rust when contacts with hot water.
Durable - To ensure that the reservoir will not break easily when it is filled with large amount hot water.
Characteristics of liquid use as a cooling agent for engine.
Specific heat capacity must be high
Not easily become hot
High boiling point Not easily boiled in high temperature
Ph7 Will not corrode the engine
rusting low Will not caused the engine to rust
Characteristics of car radiator use to cool the engine.
Large number of cooling fins
To ensure that more amount of heat is released at a short period of time.
Size of the fan is big
So that the radiator can be cooled quickly./ Direct large amount of air to the radiator. Use water Specific heat capacity of water
is high and takes time to become hot.
Use cover with spring
To ensure that pressure in the radiator can be release automatically.
Suitable characteristic of metal to be used as a cooling fins of a motorcycle
Lower specific heat of capacity
Easy to get hot or cold Higher melting point Does not melt easily Good heat conductor The heat can be lost easily Lower rate of
expansion
Essay questions
Problem solving and
decision making
5. LIGHT
How to build a compound microscope.
• Eyepiece – use longer focal length = f • Objective lens – use shorter focal length. = f • fe > fo
• Label the fe and fo
• Draw a ray diagram to show the formation of
images. Ray diagram
How to built compound microscope.
• Thicker lens as an objective lens, thinner lens as an eyepiece.
• Fo and Fe are not overlapped. • Light ray to form the first image.
• First image formed shown.
• Light ray to form final image.
• Final image formed shown. Diagram
Specification of the optical fiber use in an endoscope for medical imaging.(Mk)
Low density Lighter
High flexibility Can be bent easily. High purity Avoid loss of signal. Smaller in size Can occupied in small
space. Made from stronger
material
Not easily break
Problem solving and
How to build a compound microscope. use longer focal length = fe
use shorter focal length. = fo
formation of
Thicker lens as an objective lens, thinner lens
use in an
Can be bent easily. Avoid loss of signal.
occupied in small Not easily break
Suggest suitable modification to increase the efficiency of compound microscope. (Ktn) Eye piece has longer
focal length than objective lens.
Has higher magnification factor.
Object is place between fo and 2fo
To produce real, magnified and inverted image Adjusted so that
object for eyepiece is place u<fe
To act as a magnifying glass
Distance between lenses is > f0 + fe
To produce bigger image from the eyepiece. Store in cool and dry
place
To avoid the formation of fungus.
Design an optical instrument in the double bus so that The driver at the lower deck is able to see the upper deck. With cheaper cost. (Phg) Use periscope Cheaper than CCTV 2 plane mirrors//2
prisms
Reflect light from object Mirrors are arranged parallel light from first mirror will be reflected into second mirror
Light from second mirror is reflected into the driver’s eyes
Tube or casing to hold mirror easier to handle periscope
Mirrors are at 45o angle
Explain how to built simple periscope and suggest modification to convert the periscope to binoculars
Draw a labeled diagram
Draw a labeled diagram
Suggest suitable modification to increase the efficiency of compound microscope. (Ktn)
Has higher magnification factor.
To produce real, magnified and inverted image To act as a magnifying
To produce bigger image from the eyepiece. To avoid the formation of fungus.
Design an optical instrument in the double-decker bus so that The driver at the lower deck is able to see the upper deck. With cheaper cost. (Phg)
Cheaper than CCTV Reflect light from object Mirrors are arranged parallel light from first mirror will be reflected into second mirror
Light from second mirror is reflected into the Tube or casing to hold mirror easier to handle
Explain how to built simple periscope and suggest modification to convert the periscope to binoculars
Use 2 right angle prisms
The rays will bent through 180o
Use eye piece and objective lens
To magnified the image/ as a telescope
How you would build a simple binocular and suggest modification so the binocular will produced brighter and bigger image (J)
Objective lens with bigger diameter
More light can enter the binocular
Eyepiece with bigger power
higher power as a magnifying glass
Suitability of mirror use to watch over the shop costumer. (Pls)
Concave mirror To provide wider field view Bigger size of mirror To enable a wider view and
sharper image. Hung the mirror at
the top corner of the shop
Easier to look/won’t disturb the costumer
Characteristics of optical fiber
Small critical angle Internal reflection can easily occur
High density To have small critical angle Stiffness is low Can be easily bent
High strength Will not break easily Small in diameter Does not occupied much
space
Modify an astronomical telescope become a binocular.
• Astronomical telescope uses 2 convex lens.
Objective lens and eyepiece.
• Objective lens has longer fo. Eyepiece has
shorter fe.
Diagram
Advantage of binocular
• Binocular is shorter//smaller in size. • Easy to carry.
• Produced brighter image.
The rays will bent through To magnified the image/ as
How you would build a simple binocular and suggest modification so the binocular will produced brighter and bigger image (J)
More light can enter the higher power as a
ying glass
Suitability of mirror use to watch over the shop To provide wider field view To enable a wider view and sharper image.
Easier to look/won’t disturb
Internal reflection can To have small critical angle Can be easily bent Will not break easily Does not occupied much
Modify an astronomical telescope become a Astronomical telescope uses 2 convex lens.
. Eyepiece has
Binocular is shorter//smaller in size.
Characteristics of lenses to built telescope. Objective lens with a
long focal length
Higher magnifying power Eyepiece with a short
focal length
Higher magnifying power Objective lens with a
big diameter
Enable the light to enter and thus clearer the image to be seen
Eyepiece with a small diameter
Suitable with our eye’s size and make it easier for us to see
Design of fibre optics which can work efficiently Use refractive index
of outer layer less than the refractive index of inner layer
So that total internal reflection can happen in the fibre optic.
Use high flexibility material
So it can be bend Use stronger
material
Do no break easily Use thin material Lighter/ can be used in
small area Low density material Lighter
Suitable characteristics of lens to be used by a technician to repair watch.
Use convex lens To magnify the image % of clarity is higher Image will be brighter and
clearer
Focal length is short To increase the power/to produce bigger image/ image can be focused on the short distance Lens has smaller
diameter
Easy to wear as a spectacle. Suitable design for slide projector
Use concave mirror. To reflect dan focus light to the slide
Use two plano-convex lens that have same power
The light from the source will distribute evenly to the slide so that the image formed on the screen is brighter.
The distance between the slide and the projection lens is between f and 2f
The image formed on the screen will be magnified and real.
The slide would be placed inverted
So the image will be upright
Characteristics of lenses to built telescope. Higher magnifying power Higher magnifying power Enable the light to enter and thus clearer the image to be seen
Suitable with our eye’s size and make it easier for us to
Design of fibre optics which can work efficiently So that total internal reflection can happen in the fibre optic.
So it can be bend Do no break easily Lighter/ can be used in small area
Lighter
Suitable characteristics of lens to be used by a To magnify the image Image will be brighter and clearer
To increase the power/to produce bigger image/ image can be focused on the short distance Easy to wear as a spectacle. Suitable design for slide projector
To reflect dan focus light to the slide
The light from the source will distribute evenly to the slide so that the image formed on the screen is brighter.
The image formed on the screen will be magnified and real.
So the image will be upright
Essay questions
Problem solving and
decision making
6. WAVES
Suggest modification to built big hall so it is suitable for the assembly
Bulit a dome shaped or circular roof
Improf the aqoustic effect of sound/accomodate more student
Increase the number of door.
Reduce effect of reflection Built wall from
sound-proof material
To avoid disturbance from outside
Inner wall made from soft material/use cushion chair/curtain
To avoid reflection of sound.
Placed loudspeaker away to each other
To produce more constructive interference region
Increase the number of light
To get sufficient amount of light.
Suggest relevant steps to be taken to build a safe port for fishermen.
Built the port at the gulf
The water wave is calmer Built a wall that has a
narrow gap in the sea
The sea wave will undergoes diffraction and the amplitude will be reduced
Built the wall using concrete
Not easily to collapse Make small hole at
the wall
To absorb the wave energy.
Built stronger wall To reflect the sea wave Built higher wall The sea wave cannot pass
through over the wall The wall must be
slanting
So that the wavelength can be reduce when the sea wave hit the wall Characteristics of waves which are use to determine the depth of the sea.
High frequency sound wave
Higher energy and enable the wave to travel further Higher amplitude High energy and enable the
wave to send to further places
Higher percentage of energy reflected from seabed
So the reflected signal can be detected easily Rate of sound
absorption by the water is low
So that the wave can be easily reflected and detected by the hydrophone.
Suggestion to built beach resort
Built at bay Water is calmer. Sea is shallower
Built retaining wall Reflected back the wave to open sea.
Built gap in the wall Diffraction occurs. Energy of wave is smaller
Higher wall The wave cannot passed over the wall
Wall is built using concrete
The wall will be stronger.
Characteristics of wave use to detect a school of fish
Longitudinal wave. Sonar sound is longitudinal wave Higher frequency Has higher energy Higher speed Can travel faster in the sea Higher penetrating
power
Can penetrate through medium easily
Essay questions
Problem solving and
decision making
7. ELECTRICITY
Suggestions of material used to build heating element.
Lower density Light weight
Higher melting point Not easy to melt at high temperature
Low rate of oxidation Can be used for longer time.
Lower surface area. Resistance will be higher and produced more heat. Used longer wire Higher resistance and can
produced more heat Design of pylon for transmission of electricity. (Phg)
Use step up transformer to increase the voltage before transmission process
Current will be smaller and less loss of energy
Use low resistance wire
Less loss of energy to overcome the resistance Use low density wire Lighter. Easy to hung on
pylon.
Higher pylon For safety purpose. Not reach by others Tougher material to
build pylon. Steel alloy
Not easy to collaspe
U shape steel alloy Not too heavy Large diameter cable Less resistance
Characteristics of power socket extension for normal use. (MRSM)
Not using extension cord// use shorter extension wire
Less resistance, less loss of energy as heat energy One fuse for each
socket
If one fuse blow the other can still function Use power surge
protector.
Can cut off the supply when it is overloaded Head plug earthed Flow current leakage to
earth Suggestion to light up a room. (Pls)
Use fluorescent lamp Consume less energy Use more efficient
fluorescent lamp.
Brighter and prevent wastage of energy. Use fuse To prevent overheating of
lamp. Two or more
fluorescent lamp is connected in parallel
If one lamp blow out, the other can still function.
Specifications of lamp that is suitable to use as a reading lamp. (J)
Low power rating Consume less electrical energy
Low cost Save money//cheaper
High efficiency Produced higher output power // less energy wasted
Long lifetime Last longer Suitable design for wiring a cabin. The electric
appliances are connected in parallel//diagram
Allow each electric appliances to be switched on and off independently Fit fuse at the live
wire in the fuse box //diagram//
Use miniature circuit breakers (mcb’s)
To stop the flow of current by melting when a high voltage of electric current flows through the circuit // switches itself off very quickly if the current exceeds e.g. 15A (for 15A mcb)
Earth connection to the metal case of electrical appliances
Earth wire connected to earth, so that when a fault occurs and a current flows through the live wire and the earth wire, the fuse in the live wire will blow and cut off the supply. It will protect a person who may touch a faulty or live appliance
Use low power lamps / install fluorescent lamp
To save the energy
Use thicker wire Reduce resistance Use insulated wire To avoid short circuit Place the power
point at higher place
To avoid being touch by the children
Modification to the desk lamp so it is comfortable to use
Use a fluorescent lamp
Fluorescent lamp use less electrical energy
Use bigger cover with white color
Reduce light directly propagate to eye and reflection and reflector light and heat energy Use an adjustable
stand
Height of the lamp can be adjusted and can be used anywhere
Connect with earth wire
Flow the current leakage to the earth
Use an energy saver lamp
Use same amount of energy but light up brighter Characteristic of connecting wire
Resistance of wire is low
To prevent power loss due to heat
Melting point is higher
Prevent wire from melting at high temperature Density of wire is low So it is light weight and
reduce the mass Rate of rusting is low Prevent the wire from
rusting and can be use for longer time
Lower rate of expansion
To prevent lengthening of wire
Specification of wire used for heating element Lower density The mass is smaller and
light weight
Higher melting point Will not melt easily at high temperature
Lower oxidation rate Can be used for longer time
Higher resistance Produce more heat energy Modification to the circuit to improve safety, produce the lamps light up with normal brightness and increases the efficiency of electrical energy consuming
Attach one fuse to the live wire in the consumer unit
To break off the circuit when large current flow and produce fire Use an insulated wire To prevent short circuit Use thicker wire To reduce resistance and
improve efficiency. Attach switch for
each lamp
To allow each lamp to be switched on and off independently Connect the metal
fitting lamp to the earth wire
To flow electron (extra) to earth and avoid electric shock.
Using only 240 V light bulb
To ensure the bulbs light up with normal brightness Connect the bulbs in
parallel
Each bulbs will receive same voltage
Suitable characteristics of metal to make a water heater
Smaller surface area/diameter
The resistance will be higher
High melting point Not easy to melt Low specific heat
capacity
The temperature rise slowly
Long coiled metal To increase the resistance. Characteristics of metal use as a heater. In electrical kettle.
High resistance Higher resistance make the heating better
High melting point Not easily melt in high temperature
Low rusting effect Not easily to rust n safe for consumer
Low specific heat capacity
Easily 2 become hot
Characteristics of the current distributor cable in the car.
Low resistance A little energy is lost as heat energy
Low density Small mass and easy to be carried/hung
Wire with large diameter
To reduce the resistance Low expand rate Does not contract too
much and becomes too loose during hot days.
Suggest modifications that can be made to the electric kettle so that it can boil water faster and has better safety
Diameter of connecting wire is bigger
Less resistance and produce small amount of heat. If large current flow the wire will no be overheated Length of connecting
wire is shorter
Less resistance Heating element
must have high resistivity
Can produced high amount of heat energy with smaller current
The kettle is made from good heat insulator
Less heat loss to
surounding. Water will boil faster
Use suitable fuse. If the current flow is 8.3A. Use 13A fuse cartridge
If higher current flow the fuse will melt and kettle will no be damaged
Essay questions
Problem solving and
decision making
8. ELECTROMAGNETISM
Modification to enable moving coil microphone to detect sound effectively and generate bigger current.
Use thin diaphragm Easy to vibrate. Use stronger
material to built diaphragm
Not easy to break.
Use more number of turns of coil
Increase the rate of change of magnetic flux.
User thicker wire To reduce the resistance of wire.
Use powerful magnet to has stronger magnetic field
To increase the rate of change of magnetic flux.
Suggestion to make a hand phone charger (Phg) Use step down
transformer
Able to reduce voltage from 240V to 9V Use a diode Change ac to dc
Use capacitor Able to smooth the output current.
Suggest modification so that the galvanometer can increase its sensitivity. (J)
Increase the strength of the magnetic field
Increase the force between current carrying conductor and the magnetic field. Using lower stiffness
of hairspring
Smaller opposing force to stop the turning of the coil Lighter mass of coil Smaller inertia, able to
move easily. Increase the area of
the coil
More change to the magnetic flux, a bigger force is produced. Design of a moving coil ammeter that can function better(Mk)
Use stronger magnet Stronger magnetic field/ large rotation
Use curve magnet Produce radial magnetic field
Use cylindrical core To supply uniform magnetic field strength Use soft iron core To concentrate the
magnetic field
Use linear scale The angle of rotation is linear and more accurate Design of the ac generator so that the efficiency of the generator is higher.
Use soft iron core To concentrate the magnetic flux Increase no of turns
of coil
To increase the rate of magnetic fluxs cutting Use bigger/thicker
wire
To reduce resistance of the wire
Use curve permanent magnet
So rate of the rotation and magnetic fluxs cutting is constant
Use powerful permanent magnet
To increase the rate of magnetic fluxs change
Suggest modification to ac generator to that can produce bigger dc current. (Ktn)
Increase the number of turn of coil
Increase the rate of cutting the magnetic field
Use stronger magnet Increase the strength of the magnetic flux
Use curve magnet To provide radial magnetic field
Diameter of wire of coil is greater
Thicker wire has lower resistance. Higher current can flow.
Use copper wire Lower resistance. More current flow.
Suitable characteristics of electric bell that can produces a louder sound
Use bigger hammer So that the surface area contact is bigger/produce more impulsive force Distance between the
hammer and the gong is larger
The force applied to the gong is larger
Number of turns of the coil is larger
The strength of the magnetism is higher High curvature of the
gong
The area of air molecule vibrate is greater.
Modification to be done to enable the electric bell to ring louder
Increase the number of turns of wire
Produced greater magnetic field to produce greater force.
Increase the magnitude of current/ the number of cells
To increase the resultant of the magnetic field
Used u-shape soft iron core
Produced stronger magnetic field Use bigger diameter
of the gong
Will vibrate more air molecules
Use bigger hammer Produces greater impulsive force.
Advantage of the National Grid Network Cost of generation of
electricity is reduced
Because high voltage reduces the current flow. Reduces power loss in the cable.
Electricity supply is more reliable with less interruption.
Because repair and maintenance work can be carried at any power station and at any time. The generation of
electricity at each station can be controlled and regulated
At peak hours more generators can be switched on.
Power station can be located outside the city limits.
So that air an
environmental pollution can be reduced.
Suitable characteristics of materials to be used as a model of power transmission.
Use 12V ac power supply
Can be change the voltage with transformer
Use laminated soft iron core
Produced stronger magnet// easy to magnetize and to demagnetized Use step-up transformer Np= 1200, Ns=2400 and step-down transformer with Np=480 and Ns= 120 To increase and to decrease the voltage due to the demand/need.
Use copper wire Lower resistance. Suitable characteristics of cables use as a transmission cable.
Low resistivity To reduce heat loss in the cables
Low density The cables will be lighter Low cost Cost of project will be
lower Low rate of thermal
expansion
The cables will not expand under hot weather Modification of the loudspeaker to produce louder sound.
Increase the number of turns of coil
To increase the magnetic field strength/ current produced
Use larger diameter of wire
Reduce resistance in the coil
Cone made from lighter material
Easy to vibrate
Use stronger magnet Cone will vibrate stronger and produced more emf. Bigger diaphragm Will vibrate more air to
produce louder Cone made from
tougher material
Not easy to break.
Suitable characteristics of the hand phone charger. Connect the output
with a diode
To change a.c. current to d.c. current
Connect capacitor Smoothen the a.c. current Use the primary
turns and secondary turns with the ratio 2:1
Reduce the current to become 12V
Use soft iron core Can me magnetized n demagnetized easily and reduce the energy lost Use laminated iron
core
Increase the resistance to the flow of eddy current Wound the
secondary coil the primary coil or placed very closed to the primary
coil(along the same core)
Prevent leakage of magnetic flux
Use wire with low resistance
Reduce energy lost Use full wave
rectification circuit
To reduce loss of energy
Modification of transformer to become a step-down transformer with 12V dc output.
Connect the output with a diode
To change a.c. current to d.c. current Connect capacitor Smoothen the a.c.
current Use the primary turns
and secondary turns with the ratio 2:1
Reduce the current to become 12V
Use soft iron core Can me magnetized n demagnetized easily and reduce the energy lost
Use laminated iron core Increase the resistance to the flow of eddy current
Wound the secondary coil the primary coil or placed very closed to the primary coil(along the same core)
Prevent leakage of magnetic flux
Use wire with low resistance
Reduce energy lost
Characteristics of cable to be used in the National Grid Network.
Larger diameter To reduce the resistance of wire
Lower density The cable will be lighter and can be supported securely
The rate of expansion is low
So there is less expansion and less sagging in the cable during hot day. Higher melting point Cable does not melting in
high temperature. Problem Involving electricity Transmission Cost of cable. • Aluminum cables are
used because the density is lower (the cables become lighter), have low resistance and cheaper. Loss of power by
the cables • By using thicker aluminum cables, resistance can be reduced
• By using a high voltage
transmission, the current in the cables is reduced and the power dissipated by the cables is reduced. Charge leakage
between the cables and the earth
• To prevent charge
leakage, the aluminum cables are supported by high metal tower/pylons.
• The metal support of the
tower is earthed so that it is safe for the worker or public.
Suggestions to design a moving coil loudspeaker that can produce louder sound.
Use radial shape of magnet
The magnetic field strength is uniform. Coil is built surrounding the magnet//Attached to the magnet To increase the effectiveness of the counter react between the magnetic field.
Used lighter material to built diaphragm
Can easily vibrate. Use ac power Audio signal varies with
the current. Box made from
wood/steel
Loudspeaker is stronger.
Way to build a industrial lifting electromagnets. Large number of
turns of coil
Increase the
electromagnetic strength Use soft iron core Can be magnetized and
demagnetized easily Insulated copper
wire
Prevent short circuit Use higher
voltage/current
To produce a strong magnetic field
Use thicker wire To reduce the resistance of the coil
Design a circuit that can be used to switch on 12V dc radio Use step-down transformer Capable to reducing potential difference/voltage The ratio of no of
turn of primary coil to secondary coil must be 20:1
Can reduce 240V to 12V
Using four diodes Full wave rectification Using capacitor To smooth out output
current//produce output of steady dc
Suggest modification to the dc motor to increase the efficiency of the motor.
Increase the strength of the magnet
To increase the magnetic field strength.
Increase the number of turns of coil
To increase the magnitude of force
Increase the magnitude of current
To increase the magnitude of force/ increase the strength of the magnetic field.
Characteristics of dc motor that can be used to lift heavy object.
Lower density material
Coil has smaller mass/lighter Higher number of
turns of coil
Larger force acting on the coil. Higher
electromagnetic field strength
Stronger magnet Large force acting on the coil
More number of segment in the commutator