Resitance and Ohm's Law

Investigating Current and Voltage & Ohm's Law calculations

Resistance Calculations.

Voltage = Current x Resistance                  V = IR    volts = amps x ohms

1.       A motor has a resistance of 12 Ω. If the supply voltage is 6 V calculate the current flowing through it.

I = V/R = 6/12 = 0.5A

2.       A current of 0.55 A flows through a resistor of value 22 Ω. Calculate the voltage across the resistor.

V = IR = 0.55 x 22 = 12.1V

3.       See circuit diagram opposite. A bulb has a resistance of 9 Ω. The reading on the ammeter is   0.17 A. Calculate the reading on the voltmeter.

V = IR = 0.17 x 9 = 1.53V

4.       A motor has resistance of 210 Ω. A voltmeter placed in parallel with the motor reads 5 V. calculate the current flowing through the motor.

I= V/R = 5/210 = 0.024A

5.       A power supply is set to 9V. Calculate the current flowing through a 1.2 kΩ resistor.

1.2kΩ = 1200Ω Using I=V/R = 9/1200 = 0.0075A

6.       A torch bulb is connected to a 3V battery. It has a resistance of 8.5 Ω. Calculate the current flowing through it.

I = V/R = 3/8.5 = 0.35A

7.       A light bulb is connected to a 240V supply. A current of 0.24 A flows throug it. Calculate the resistance of the bulb.

R=V/I = 240/0.24 = 1000Ω

8.       An electric drill is connected to a 240V supply. A current of 4 A flows through it. Calculate its resistance.

R=V/I = 240/4 = 60Ω

9.       The reading on the ammeter in the circuit opposite is 1.69 A. The reading on the voltmeter is 10.9 V. Calculate the resistance of the bulb.

10.   R=V/I = 10.9/1.69 = 6.5Ω