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Physics
Ohm’s Law
Questions
and
Answers
Beath High School - Int 1 Physics
1
1.
A resistor has a voltage across it of 12 volts and a
current through it of 2.5 amperes.
Calculate the resistance of the resistor.
resistance =
voltage
current
12
=
2.5
= 4.8 W
Beath High School - Int 1 Physics
2
2. A voltage of 6 volts is across a resistor where the
current is 0.5 amperes.
What is the value of the resistor?
resistance =
voltage
current
6
=
0.5
= 12 W
Beath High School - Int 1 Physics
3
3. Calculate the resistance of a component when a
voltage of 24 V causes a current of 0.1 amperes.
resistance =
voltage
current
24
=
0.1
= 240 W
Beath High School - Int 1 Physics
4
4. If a current of 2 amperes exists through a lamp when
it has 12 volts across it, what is the resistance of the
lamp?
resistance =
voltage
current
12
=
2
= 6W
Beath High School - Int 1 Physics
5
5. A torch bulb is marked "6 V, 0.25 A".
Calculate the resistance of the bulb.
resistance =
voltage
current
6
=
0.25
= 24 W
Beath High School - Int 1 Physics
6
6. A resistor is placed in a circuit. The voltage across it
and current through it are measured as 12 volts and
0.02 amperes.
The resistor is now removed from the circuit and an
ohmmeter connected across it.
What is the reading on the ohmmeter?
resistance =
voltage
current
12
=
0.02
= 600 W
Beath High School - Int 1 Physics
7
7.
Find the values of the resistors in the circuit
below.
2V
3V
5V
V
V
V
R1
R2
R3
0.25 A
V
2
R1 =
=
= 8W
I
0.25
R2
R3
V
3
=
=
= 12 W
I
0.25
V
5
=
=
= 20 W
I
0.25
Beath High School - Int 1 Physics
8
8. A resistor of resistance 50 W is placed in a circuit.
The voltage across it is measured as 12 volts.
What is the current in the resistor?
current =
voltage
resistance
12
=
50
= 0.24 A
Beath High School - Int 1 Physics
9
9. A 15 W resistor is connected to a 9.0 V
battery.
What is the current in the resistor?
current =
voltage
resistance
9
=
15
= 0.60 A
Beath High School - Int 1 Physics
10
10. A 25 W resistor is connected to a battery.
The current in the resistor is 0.25 A.
What is the voltage of the battery?
voltage = current x resistance
= 0.25 x 25
= 6.25 V
Beath High School - Int 1 Physics
11
11. A 480 W resistor is connected to a battery.
The current in the resistor is 26 mA.
What is the voltage of the battery?
voltage = current x resistance
= 0.026 x 480
= 12.48 V
Beath High School - Int 1 Physics
12