1. Chapter 19 Pretest Current and Resistance

2. 1. A current of 5.0 A moves for 10 s. What total charge passes?

3. I = q/t It = q 5.0 x 10 = q 50 C = q

4. 2. A 60 Ω resistor carries 7.0 A. What is the potential difference across this resistor?

5. V = IR V = 7.0 x 60 V = 420 V

6. 3. List 4 things that affect resistance of a conductor. What effect do they have?

7. 1. Length - the longer the wire, the higher the resistance 2. Cross section – the “fatter” the wire, the lower the resistance 3. Material – some materials are better conductors than others 4. Temperature – the higher the temperature, the higher the resistance

8. 4. A 600 W stove has a current of 15 A. What is the potential difference across the stove?

9. P = IV 600 = 15 V 40 V = V

10. 5. A microwave draws 5.0 A when connected to a 120 V outlet. If electrical energy costs $0.090/kWhr, what is the cost of running the microwave for exactly 6 hours?

11. P = IV P = 5 x 120 P = 600 W 600 W / 1000 = 0.600 kW 0.600 kW x 6 hours = 3.6 kWh 3.6 kWh x 9 cents = 32.4 = 32 cents