03 Electric Current.pptx

Experimenter A uses a test charge q₀ and experimenter B uses a test charge -2q₀ to

measure an electric field produced by stationary charges. Experimenter A finds

a field that is:

a) The same in both magnitude and direction as the field found by B

b) Greater in magnitude than the field found by B c) Less in magnitude than the field found by B

d) Opposite in direction to the field found by B

a) The same in both magnitude and direction as the field found by B

b) Greater in magnitude than the field found by B c) Less in magnitude than the field found by B

The figure here shows four situations in which charged particles are at equal

distances from the origin. Rank the

situations according to the magnitude of the net electric field at the origin.

a) a < b < c < d

b) d < c < a = b

c) c < a < b < d

d) a = b = c = d

• _{model charges flowing through a wire using}

the analogy of water flowing through a pipe.

• _{know the common and fundamental units of}

electrical current and resistance.

• _{know the relationship between voltage,}

current, and resistance.

• _{know the relationship between power,} voltage, and current.

1 DOZEN eggs

12 eggs

1 REAM of paper

500 sheets

1 BUSHEL of apples

2152.42 cubic inches

COULOMB

A whole heck of

a boophoo bunch

of charge

ONE COULOMB of charge (+ or -) Equals

6.24 x 10

18

charges

GRAVITATIONAL

Potential Energy

Separating

Attractive Bodies

ELECTRICAL

Potential Energy

Bringing Together Repulsive Bodies

2,000 N

ELECTRICAL

Potential

(Voltage)

(Joules/Coulomb)

ELECTRICAL

Potential

Energy

(Joules)

Total amount

of energy

Total amount

of energy

for EACH

coulomb of charge

Electrical Current

is like

1 ft3 1 ft3

1 ft3 _{1 ft}3

1 ft3 _{1 ft}3

1 ft3 1 ft3

1 ft3 1 ft3

1 ft3 1 ft3

1 ft3 _{1 ft}3

1 ft3 1 ft3

1 ft3 1 ft3

1 ft3 1 ft3

12 ft3

12 ft3

http://www.outrageousadventures.co.za/photogal/kz%20bivane.htm

1 ft3 1 ft3 1 ft3 1 ft3 _{1 ft}3 1 ft3

1 ft3 1 ft312 ft1 ft3 1 ft3 _{1 ft}3 1 ft3

3

1 ft3 1 ft3 1 ft3 1 ft3 _{1 ft}3 1 ft3

1 ft3 1 ft3 1 ft3 1 ft3 _{1 ft}3 1 ft3

1 ft3 1 ft312 ft1 ft3 1 ft3 _{1 ft}3 1 ft3

3 12 ft3

12 ft3

River “Flow” = (CFS)

Feet

Second

http://media-2.web.britannica.com/eb-media/75/94675-004-518A2065.jpg

Mississippi River

500,000 CFS

Clear Creek

Electrical CURRENT

The number of electrons

that “flow” by a given point each second.

UNITS?

“Amps”

Coulombs

Second

12 Amps = 12 Coulombs per second

Which wire has more CURRENT running through it?

Which wire has more CURRENT running through it?

A

B

C

http://www.gd-wholesale.com/userimg/58/2718i1/nickel-metal-hydride-ni-mh-rechargeable-battery-933.jpg

5000 mAh

5000 milli-Amp ∙ hours

5000 1/1000th-Amp ∙ hours 5 Amp ∙ hours

5 Ah

http://toolmonger.com/wp-content/uploads/2006/05/standarddrill.jpg http://www.mytoolstore.com/milwauke/battery.html

If a drill uses

3.2 Amps,

how long will this

battery last?

1 Amp 2.6 Hours 1.3 Amps 2 Hours 2.6 Amps 1 Hour 3.2 Amps .81 Hours

http://www.mytoolstore.com/milwauke/battery.html

How many

electrons

are

transferred

by the time the

battery is used up?

2.6 Amp·hours

2.6 Coulombs_sec hours 3600 sec hour

6.24 x 1018 electrons

Coulomb

+ + + + + + + + ++ + + + + + + + + + + + + + + + + + + + + + +

Current is directly proportional to Voltage

+ + + + + + + + ++ + + + + + + + + + + + + + + + + + ++ + + + + + + + + +

Voltage =

·

K

Resistance =

Voltage

_Current

UNITS?

Coulombs second

Joule·Seconds

Coulomb2

Andre

Ampere Georg_Ohm Alessandro

Volta

=

·

Voltage = Current · Resistance

V = I · R

A Amps I Current  Ohms R Resistance V Volts V

Voltage _CoulombJoules

Coulombs Second

Joule ·Second Coulomb2

V = 12 V

I = 4 A

R = 3



Fundamental Unit Symbol for Unit Common Unit Symbol for Concept Concept

Voltage = 12 Volts

Current = 4 Amps

Resistance = 3 Ohms

N Newtons

F

·

1

slope

Amps Volts

V = I · R

100 W

Power = Voltage · Current

P = V · I

Watts

Joules

Coulomb

Coulomb

Second

=

·

P = I

· R

Power = Current

· Resistance

Watts

Coulombs

Second

Joule·Second

Coulomb

=

·

= ?

6 kilowatts

(6,000 Watts)

6 kilowatts

(6,000 Watts)

Power = Voltage · Current

Learning Goal

To gain a

CONCEPTUAL UNDERSTANDING

of each of the following

electrical terms:

=

·

Joules Coulomb

Coulombs Second

V = I · R

Power = Voltage · Current

P = V · I

P = I

2

· R

Power = Current

· Resistance

Resistance (Impedance)

“Ohms”

Current = Current

Current = Current

z

• _{model charges flowing through a wire using}

the analogy of water flowing through a pipe.

• _{know the common and fundamental units of}

electrical current and resistance.

• _{know the relationship between voltage,}

current, and resistance.

• _{know the relationship between power,} voltage, and current.