Science 4 - Electrical Science

If the voltage across a resistor is doubled, what happens to the current?

• There is no change to the current

• The current doubles

• The current halves

• It is impossible to say

Answer explanation

If the resistance stays the same, when the voltage doubles, the current must also double to keep the ratio the same.

What current will flow through a 120 Ω resistor if 6 V is applied across it?

• 0.05 A

• 0.04 A

• 0.02 A

• 0.01 A

Answer explanation

A circuit has a resistance of 100 Ω and a supply of 220 V. What power is dissipated by the resistor?

• 2.2 W

• 320 W

• 484 W

• 22,000 W

Answer explanation

A resistor is to be used on a 5 V supply and is expected to have a current of 0.08 A flowing through it. Which of the following power ratings would NOT be suitable for the resistor?

• 0.25 W

• 0.5 W

• 1.0 W

• 2.0 W

Answer explanation

The resistor will dissipate 0.4 W, which would exceed the 0.25 W rating. In this case, any resistor with a power rating less than 0.4 W would be unsuitable.

A circuit has a load of 350 Ω and a supply of 9 V. What power is dissipated?

• 231.4 mW

• 3150 W

• 13.61 kW

• 28.35 kW

Answer explanation

A resistor is connected to a 6 V supply and a current of 0.12 A flows through it. What power does it dissipate?

• 0.0024 W

• 0.72 W

• 4.32 W

• 300 W

Answer explanation

A 47 Ω resistor placed in a circuit has 0.24 A flowing through it. What power does it dissipate?

• 0.001 W

• 2.7 W

• 530 W

• 9204 W

Answer explanation

What is the total resistance of these two resistors connected in series?

• 15 kΩ

• 22 kΩ

• 47 kΩ

• 69 kΩ

Answer explanation

What is the total resistance of these three resistors connected in series?

• 953.3 Ω

• 4.25 kΩ

• 4,000 Ω

• 12.8 kΩ

Answer explanation

What single resistor could replace two 5 kΩ resistors connected in parallel?

• 1.0 kΩ

• 2.5 kΩ

• 5.0 kΩ

• 10.0 kΩ

Answer explanation