Electricity Student Note Packet.doc

NOTE PACKET

“Electricity &

Magnetism”

NOTE

packet

I. OUTCOME 1:

__________________________

A. Review: atomic structure

B. Charge is measured in units called _________________________ (C). C. Objects can have a _________________ or ___________________ charge. D. _____________________ = overall charge of an object, caused by an

__________________or ___________________ of ______________________. 1. More electrons than protons = ___________________ charge

2. More protons than electrons = ___________________ charge

3. Equal protons and electrons = ___________________ (__________________)

II. OUTCOMES 2: Electrically Charged Objects

A. Charged objects affect each other due to _______________________________. 1. Caused by attraction or repulsion of ____________________.

2. Same charges ___________________ Opposite charges __________________

4. _________________________ is the area in which one charged object can affect another object(s) (how __________ the force can reach).

B. __________________ Electricity = _______________________ from one object to another creating a tiny _________________________________ on an object.

~VERY tiny = less than ______________________________!

1. When two _______________ objects rub together, ______________________ from one to another.

Ex. When you rub your feet across the carpet, ____________________ ____________________________________.

This leaves each object _________________________________. 2. When you touch _______________________________, the

______________________ quickly move __________ your body = _________________________ = ________________________!

C. _____________________ = used to observe the _____________________ between charges.

1. ________________________ – Something that __________________________ ____________________________.

2. In a conductor, ________________________________ and _______________________________ when possible.

3. ____________________ – Something that has ____________________, so it can’t carry _________________.

Examples: ____________________________________________________

4. How the electroscope works:

a) __________________ charged object (like a ________________) brought close to the metal…

b) electrons in the metal are _______________ by the negative balloon, and move ___________.

III. OUTCOME 3: How Objects Become Charged

A. Charging by __________________: If you touch a ________________________ ___________________________________ object to the electroscope,

____________________________________________________________________ giving it a ______________ charge.

~Can be used to _______________________________________ B. Charging by ____________________: Rubbing a balloon on your head

______________________ from your hair to the balloon, giving your hair a

__________________ charge and the balloon a _____________________________ charge.

C. __________________________: When the ________________________________ sides of atoms in an object _______________________________________.

When you put a charged balloon on the wall, what happens?

1) Negatively charged balloon causes electrons in the wall to move ___________ _______________________________________________.

2) Atoms of the wall are now ___________________________________ ________________________________________.

D. Charging by _______________________: Using _____________________________ ________________without changing the __________________________________ object.

~_____________________________________________, thereby creating a _______________ charged object.

IV. Outcomes 4: Electric Circuits

A. Electric ________________ = continuous ___________ of electric _______________. 1. Caused by the flow of ________________.

Which direction? Electrons flow from _________ to _____________ Flow of electrons…..

2. Direction of _______________ is defined as from + to – (the way _____________ _________________ would move).

3. Materials and electricity

a. Electrical _________________ = electrons are _________________________ ____________________, so current _______________ easily.

Examples: _________________________________________________

***The electrons that move come from the atoms in a ____________, not the BATTERY!!!***

b. Electrical ________________ = electrons are __________________________ so current cannot flow easily.

Examples: ______________________________________ Conductor, Semiconductor, Insulator

Superconductors:

Some materials give _________________________ to current when they are _____________________________________________________.

Example: Niobium-Zirconium alloy

Conductor (free electrons)

Semiconductor (some free electrons)

Insulator (no free electrons) Battery

+

B. Electric ______________ = a complete _____________ through which charge can flow.

1. Circuit diagrams or _________________ diagrams

a. Use __________________ to represent parts of a circuit.

b. Neat and clear: easy to understand (if you know something about electricity)

c. Easier to plan and design circuits.

2. _______________________ = charge cannot flow (switch is ___________) ____________________ = path is complete, charge flows (switch is _________) 3. Two types of Circuits:

a. _________________ circuit = charge has only ___________ path through which it can flow.

- What happens if ANY ONE part of the circuit stops working?

o __________________________________________________________

- What happens if you add bulbs or other energy users to the circuit?

b. __________________ circuit = _______________ paths through which charges can flow.

- What happens if one part of the circuit stops working?

o ________________________________________________________

- What if you add bulbs or other energy users to the circuit?

4. Safety

a. ________________________: electricity taking ________________________ ___________________.

- A short circuit is one with no ________________ (no ________________) - When this happens energy is converted to ____________ and can start a fire! b. Fuses (and circuit breakers) = Used to prevent _____________________ by

_____________________ the circuit if too much current passes through (“blowing a fuse”).

V. Outcomes 5: Ohm’s Law – Current, Voltage,

Resistance.

A. Ohm’s Law

1. DEMONSTRATION Set-up: Imaginary water lab <> Drops of water = ____________________ <> Flow rate of water = ___________________

<> Water pressure (determined by ____________________) = _____________________________

<> Tube = _______________________

<> Size of tube = ________________________

>>>What causes water to flow? ___________________________________ 2. Electric Current = continuous flow of electric charge, measured in units of

3. ____________________ = a measure of ________________________________, caused by a difference in ______________________________

a. Voltage ____________________ causes ____________________________. b. Measured in units of __________________.

c. Battery = uses ________________________ to create a

________________________________ between two terminals (+ and -). d. Amount of voltage ______________________________ as current flows

through a circuit.

e. How does voltage affect current?

Back to the Demo: How does _____________________ affect ____________________?

To change the pressure, we change the _______________ of the water.

What happens when the height is increased? Does the bucket fill more or less quickly? _______________

So, the higher the voltage, the ____________________ current.

(A Battery would act like a _________________ to bring water back to the top in a circuit, allowing ________________________________)

4. Resistance = _____________________________________________________ flowing through it (how ____________________ it is for current to flow through) ~high resistance = ___________________ for current to flow = ______________

________________________.

~low resistance = __________________ for current to flow = _______________ _________________________.

b. How does resistance affect current?

Back to the Demo: How does _____________________ affect __________ __________________________?

<> Increasing the tube size represents _____________________________. <> What happens? Does the bucket fill more or less quickly? ____________

So, the lower the resistance, the _____________________________ current.

5. Ohm’s Law

Voltage = ______________ x ________________

Example 1. If a toaster produces 12 ohms of resistance in a 120-volt circuit, what is the amount of current in the circuit?

D. Current, Voltage, Resistance, and Ohm’s Law: Series vs. Parallel Circuits

Series Circuit Parallel Circuit

# of paths

Current

Voltage

Resistance

1 SERIES CIRCUIT Practice Problem

a What is the total voltage across the bulbs?

b What is the total resistance of the circuit?

c What is the current in the circuit?

d What is the voltage drop across each light bulb? (Remember that voltage drop is calculated by multiplying current in the circuit by the resistance of a particular resistor: V = IR.)

2. PARALLEL CIRCUIT Practice Problem

a What is the voltage across each bulb?

b What is the current in each branch?

c What is the total current provided by the battery?

d Use the total current and the total voltage to calculate the total resistance of the circuit.

V. Outcome 6: Power and the Cost of Electricity

A. Electrical _____________ = _____________ at which electrical ____________ is changed into _____________________________________

Examples:_______________________________________________ 1. Measured in ________________

2. Calculating power

Power = ________________ x __________________

Example: A 12-volt battery is connected in series to two identical light bulbs. The current in the circuit is 3 A. Calculate the power output of the battery.

B. Buying electricity

2. We buy _________________________________________ = how many ________________ of watts are used

________________________________________________ is used for.

Example: You use a 1,500 watt hair heater for 3 hours. How many kilowatt-hours of electricity did you use?

How much did it cost of electricity is 9 cents per kWh? C. Types of Current

1. DC = __________________________ = Current always flows

_____________________________ from the ___________________ toward the ______________________.

Example: Current from a ______________.