Question

1) A 1.5V battery connects to a 10 ? resistor. The power dissipated by the resistor is:

a)	15 W
b)	0.15 W
c)	0.23 W
d)	22.5 W

2) A student plugs a device into a U.S. wall outlet (V_rms = 120 V) and measures the peak current through the device as I = 2.0 A. What is the average power used by the device?

a)	60 W
b)	240 W
c)	170 W
d)	120 W

Answer 1

Question 1

Voltage of the battery = V = 1.5 V

Resistance of the resistor = R = 10

Power dissipated by the resistor = P

P = 0.23 W

Power dissipated by the resistor = 0.23 W

Question 2

RMS Voltage of the wall outlet = V_rms = 120 V

Peak current through the device = I_max = 2 A

RMS Current through the device = I_rms

I_rms = 1.414 A

Average power used by the device = P

P = V_rmsI_rms

P = (120)(1.414)

P = 170 W

Average power used by the device = 170 W