1. General Physics 2Current & Resistance1 Electric Currents (R)

2. General Physics 2Current & Resistance2 Resistors (L) circuit symbol what is the resistance of this resistor? Try some others.

3. General Physics 2Current & Resistance3 Electric Power (L) Power = Energy / time Other useful forms:

4. General Physics 2Current & Resistance4 Think-Pair-Share (L) You buy a 75-W lightbulb in Europe, where electricity is delivered to homes at 240 V. If you use the lightbulb in the US at 120 V (assume its resistance does not change), how bright will it be relative to 75-W 120-V bulbs? [Hint: assume that brightness is proportional to power consumed.]

5. General Physics 2Current & Resistance5 Think-Pair-Share (L) How many kWh of energy does a 550-W toaster use in the morning if it is in operation for a total of 15 min? At a cost of 9.0 cents/kWh, estimate how much this would add to your monthly electric bill if you made toast four mornings per week.

6. General Physics 2Current & Resistance6 Power in Household Circuits (L) Wires heat up at a rate equal to I 2 R (power) fire hazard if I is too large fuses prevent overloads by breaking circuit short - two wires touching

7. General Physics 2Current & Resistance7 Fuses (L) fuses that need to be replaced circuit breaker- breaks circuit with a switch

8. General Physics 2Current & Resistance8 Household Circuits (L) What is the total current draw by these devices? If the circuit has a 20-A fuse, will the fuse blow?

9. General Physics 2Current & Resistance9 Alternating Current (L) DC direct current current is constant AC alternating current current varies like a sine wave frequency usually 60 Hz (60 cycles per second) Equations are valid when you use RMS values

10. General Physics 2Current & Resistance10 Human Nervous System (L) Messages transmitted within nervous system are electrical signals passing along the neuron

11. General Physics 2Circuits11 Practice Problems Determine the equivalent resistance and the current through R 1 for the circuits shown. Assume R 1 = 10 , R 2 = 20 , and R 1 = 30 , and the battery is 12 V.