PHYS 135B Homework Set 7
Dr. Zorba
Chap ter 19 :
1-) P1 Calculate the terminal voltage for a battery with an internal resistance of
Ω900.0
and an emf of 8.50 V when the battery is connected in series with (a) an
Ω-0.81
resistor, and (b) an
Ω-810
resistor.
2-) P9 Suppose that you have a
,-680 Ω
a
,-940 Ω
and a
Ωk-20.1
resistor. What is (a)
the maximum, and (b) the minimum resistance you can obtain by combining
these?
3-) P20 What is the net resistance of the circuit connected to the battery in Fig.
19–41? Each resistance has
.k8.2 Ω=R
4-) P31 A 120-V hair dryer has two settings: 850 W and 1250 W. (a) At which
setting do you expect the resistance to be higher? After making a guess,
determine the resistance at (b) the lower setting; and (c) the higher setting.
5-) P34 At $0.095 per kWh, what does it cost to leave a 25-W porch light on day
and night for a year?
6-) P42 Calculate the peak current in a 2.2-kΩ resistor connected to a 220-V rms
ac source.
7-) P46 An 1800-W arc welder is connected to a 660-Vrms ac line. Calculate (a) the
peak voltage and (b) the peak current.
8-) P48 A heater coil connected to a 240-Vrms ac line has a resistance of 34 Ω (a)
What is the average power used? (b) What are the maximum and minimum
values of the instantaneous power?