17 Electricity 2019 JnN

A voltmeter and an ammeter are used to measure the resistance of a resistor.

Which diagram shows the voltmeter and the ammeter correctly connected?

A student sets up four circuits.

In which circuit is there a heater in series with a fuse?

An electric heater is plugged into the mains supply using a fused plug.

The current in the heater is 10 A. The cable attached to the heater is rated at 15 A. The fuses available are rated at 1 A, 3 A, 5 A and 13 A.

Which fuse should be used?

• 1 A

• 3 A

• 5 A

• 13 A

The diagram shows a circuit containing a d.c. power supply, a motor and a variable resistor. Three ammeters X, Y and Z show the current in different parts of the circuit. The reading on X is 4.0A. Which statement is correct?

• The readings on Y and Z are both less than 4.0A.

• The readings on Y and Z are both equal to 4.0A.

• The readings on Y and Z are both greater than 4.0A.

• The reading on Z is zero.

A lamp is to be connected in a circuit so that the potential difference (p.d.) across it can be varied from 0 to 6 V.

Which circuit would be most suitable?

What is connected in parallel with the thermistor?

• heater

• lamp

• light-dependent resistor

• variable resistor

The circuit shows a relay being used to operate a mains lamp. Two ammeters are labelled P and Q. The variable resistor is used to vary the current in the relay coil. The mains lamp switches on when there is a large enough current in the relay coil. The graph shows how the reading on ammeter Q changes as the reading on ammeter P increases.

What is the minimum current needed in the relay coil to switch on the mains lamp?

• 0.15 A

• 0.20 A

• 0.35 A

• 0.60 A

Which components are designed to improve the safe working of a mains electrical supply?

A battery stores chemical potential energy. The battery is connected to a resistor. As the battery runs down, what happens to its chemical energy?

• The energy is transferred by electrical working and ends up as internal energy in the resistor

• The energy is transferred by electrical working and ends up as potential energy in the resistor

• The energy is transferred by mechanical working and ends up as internal energy in the resistor

• The energy is transferred by mechanical working and ends up as potential energy in the resistor

The bell is ringing but the lamp is not lit.

Which switches are closed?

• S1 only

• S1 and S2 only

• S1 and S3 only

• S1, S2 and S3