Ohm's Law Problems

Question 1

An alarm clock draws 0.5 A of current when connected to a 120 volt circuit.
Calculate its resistance.

a) 150 ohms
b) 120 ohms
c) 60 ohms
d) 240 ohms

Question 2
If one 9 volt battery is used in a circuit with a total resistance of 39 ohms, what is the current in the circuit?

a) 0.35 amps
b) 351 amps
c) 23 amps
d) 0.23 amps

Question 3
A waffle iron has 12 amp current. If the resistance of the coils is 10 ohms what must the voltage be?

a) 240 volts
b) 1.2 volts
c) 120 volts
d) 12 volts

Question 4
The wire in a series circuit has a resistance of 8 ohms and the light bulb in the circuit has a resistance of 14 ohms. A 66 volt battery provides energy to the entire circuit. What is the current through the entire circuit?

a) 4.71 amps
b) 8.25 amps
c) 30 amps
d) 3 amps

Question 5
The break light on a car is connected to a 12-V battery. If the resulting current is 0.4 amps, what is the resistance of the brake light?

a) 30 ohms
b) 4.8 ohms
c) 5.3 ohms
d) 3 ohms

Question 6
A circuit has a resistance of 30 ohms and a current of 0.05 amps, what is the voltage of the battery?

a) 15 volts
b) 12 volts
c) 9 volts
d) 1.5 volts

Question 7
An electric heater works by passing a current of 100 amp though a coiled metal wire, making it red hot. If the resistance of the wire is 1.1 ohms, what voltage must be applied to it?

a) 220 volts
b) 120 volts
c) 110 volts
d) 90.9 volts

Question 8
What current flows through a hair dryer plugged into a 120 Volt circuit if it has a resistance of 25 ohms?

a) 5.3 amps
b) 0.20 amps
c) 4.8 amps
d) 0.5 amps

Question 9
A subwoofer needs a household voltage of 110 V to push a current of 5.5 amps through its coil. What is the resistance of the subwoofer?

a) 2.0 ohms
b) 0.05 ohms
c) 20 ohms
d) 30 ohms

Question 10
If three 1.5 volt batteries are put into a flashlight and the resistance across the light bulb is 30 ohms, what is the current going through the light bulb?

a) 0.15 amps
b) 10 amps
c) 0.05 amps
d) 0.5 amps.