9 Ohm's Law - Presentation

Multiple Choice

A resistor carries a current of 0.25 A when connected to a 6 V supply.
Calculate the resistance of the resistor.

• 1.5

• 24

• 0.04

• 2.5

Multiple Choice

A car headlight operates on a 12 V battery and draws a current of 3.5 A.
Calculate the resistance of the headlight.

• 42 Ω

• 3.4 Ω

• 0.29 Ω

• 15.5 Ω

Multiple Choice

An electric kettle has a resistance of 48 Ω.
Calculate the current when connected to a 240 V supply.

• 5 A

• 0.2 A

• 288 Ω

• 192 A

Multiple Choice

A motor with a resistance of 30 Ω is connected to a 9 V battery.
Calculate the current flowing through the motor.

• 0.3 A

• 3.3 A

• 270 A

• 9 A

Open Ended

A heater coil has a resistance of 60 Ω and carries a current of 4 A.
Calculate the voltage across the heater coil.

Open Ended

A lamp connected to a 12 V supply draws a current of 0.4 A.
If the voltage is increased to 18 V, calculate the new current (resistance constant).

Open Ended

A resistor has a resistance of 200 Ω at room temperature and a current of 0.05 A flows through it.
If the resistance doubles when it heats up, calculate the new current if the voltage stays the same.

Open Ended

A phone charger provides a voltage of 5 V and a current of 2 A.
Calculate the resistance of the charger’s circuit.

Open Ended

A power tool motor draws 6 A when connected to a 120 V supply.
Calculate the resistance of the motor.

Open Ended

A filament bulb draws a current of 0.2 A when connected to a 240 V source.
Calculate the resistance of the bulb.

Open Ended

A resistor has a resistance of 100 Ω.
Calculate the current when it is connected to:
a) a 10 V supply, and
b) a 20 V supply.
Explain how doubling the voltage affects the current.