1. The power of electricity

2. AWESOME !!!!!

3. “Sin City”, Las Vegas, Nevada

4. Christmas with a vengeance!! UFO’s stopping by to see
The pretty lights.

5. Solve the following circuit problems:
Last night’s homework
Solve the following circuit problems:
(USE ALL 6 STEPS!)
V = 6 v I = 2 amps. R = ?
V = 8.5 v I = ? R = Ω
V = ? I = 9 amps. R = 10 Ω
The heater fan on the #33 bus is on a 7 amp. circuit.
The bus has a 24 v battery. What is the resistance
of the fan motor?

6. 1. V = 6 v I = 2 amps. R = ? R = ? V = 6 v I = 2 amps. V = I x R
6 v = 2 amps. x R
6 v = 2 amps. x R
2 amps. = 2 amps.
6 v/2 amps. = R
3 Ω = R

7. 2. V = 8.5 v I = ? R = 2.125 Ω R = 2.125 Ω V = 8.5 v I = ? V = I x R
4 amps. = I

8. 3. V = ? I = 9 amps. R = 10 Ω R = 10 Ω V = ? I = 9 amps. V = I x R
V = 9 amps. x 10 Ω
V = 90 v

9. 4. V = 24 v I = 7 amps. R = ? R = ? V = 24 v I = 7 amps. V = I x R
24 v = 7 amps. x R
24 v/7 amps. = R
3.429 Ω = R

10. U3e-L2
Electrical Power
Electric Power – the rate at which electrical energy is used by a Load.
Units of power are the Watt (W)
A human climbing a flight of stairs is doing work at a rate of about 200 watts.

11. U3e-L1
Joule’s Law
James Joule (1818 – 1889) – showed that heat and electrical energy are interchangeable.
Joule’s Law:
Power = Voltage x Current
P = V x I
Watts = Volts x Amperes

12. Problems – Joule’s Law 2. Table 1. Diagram 3. Formula, solve P = V =
P = V x I

13. A cell phone charger provides 5 volts (DC) to charge the cell phone
A cell phone charger provides 5 volts (DC) to charge the cell phone. The amount of current that the charger delivers is .7 Amperes. What is the power used by the cell phone in recharging its battery?
P = ?
V = 5v
I = .7amps.
V = 5v
I = .7amps.
P = ?
P = V x I
P = 5V x .7A
P = 3.5 W

14. What is the resistance of the cell phone?
V = I x R
5v = .7amps. x R
5v/.7amps. = R
7.14 Ω = R

15. Formulae and calculations only! YEAAAAAAA!
CLASSWORK
Formulae and calculations only! YEAAAAAAA!
P = 25 W V = 100 v I = ? R = ?
P = ? V = 12 v I = ? R = 6 Ω

16. CLASSWORK (cont’d) P = 100 W V = ? I = 2.5 amps. R = ?
P = 1400 W V = 120 v I = ? R = ?

17. HOMEWORK
A Honda Insight (hybrid) has a 144 volt battery. The electric motor that the battery powers uses 20,000 Watts of power. What is the current in this circuit? What is the resistance of the motor?
( 1 diagram, 1 table, 2 formulae, 2 calculations.)

18. ( 1 diagram, 1 table, 2 formulae, 2 calculations.)
2. A curling iron uses a 120v power source (AC). The current in the circuit is
12.5amps. What is the power of the curling iron? What is the resistance of
the curling iron?
( 1 diagram, 1 table, 2 formulae, 2 calculations.)

19. ( 1 diagram, 1 table, 2 formulae, 2 calculations.)
3. An electric fan has a power of 600 W. The voltage is 120 v (AC). What is the current in this circuit? What is the resistance of the fan motor?
( 1 diagram, 1 table, 2 formulae, 2 calculations.)