17 Electricity 2022N

Which description of a current in a metal is correct?

• a flow of electrons

• a flow of molecules

• a flow of positive atoms

• a flow of protons

The diagram shows a circuit containing a variable resistor connected to a variable power supply.

The table shows the currents for different values of the potential difference (p.d.) and the resistance.

What is the order of the currents from smallest to largest?

• I₁ → I₂ → I₃

• I₁ → I₃ → I₂

• I₂ → I₁ → I₃

• I₃ → I₁ → I₂

The e.m.f. of the cell in this circuit is 1.5 V.

What does e.m.f. stand for?

• electromagnetic field

• electromagnetic force

• electromotive field

• electromotive force

A student finds the resistance of a resistor.

Which circuit is used to measure the potential difference (p.d.) across the resistor and the current in it?

The circuit diagram shows a variable potential divider.

The slider is moved from P towards Q.

What happens to the reading on the voltmeter and to the brightness of the lamp?

• decreases, decreases

• decreases, increases

• increases, decreases

• increases, increases

The diagram shows a circuit containing a cell, a variable resistor, and two bulbs, P and Q.

The resistance of the variable resistor is increased.

What happens to the brightness of each bulb?

• dimmer, dimmer

• dimmer, remains the same

• remains the same, dimmer

• remains the same, remains the same

Which diagram shows a circuit containing a battery, a fuse and a buzzer?

Why is a fuse used in an electric circuit?

• to increase the circuit resistance

• to prevent short circuits

• to reduce the power loss

• to stop the cables from overheating

An electric hairdryer is rated 230 V, 2 A.

Which circuit could be used to check that these ratings are correct?

The diagram shows a circuit used to control the potential difference (p.d.) across a lamp.

The variable resistor is adjusted until the p.d. across the lamp is 6.0 V.

The current in the lamp is 0.5 A.

What is the resistance of the lamp?

• 0.083 Ω

• 3.0 Ω

• 6.5 Ω

• 12.0 Ω