CAIE IGCSE Physics 4.2.2 Electric Current Topic Practice

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Covered syllabus points

4.2.2.1—Electric current is related to the4.2.2.2—Use of ammeters (analogue and digital)4.2.2.3—Electrical conduction in metals in4.2.2.4—Difference between direct current4.2.2.5—Electric current as charge passing a4.2.2.6—Conventional current is from positive

Question 1

[Maximum number: 1]

A circuit contains two fixed resistors and a light-dependent resistor (LDR). Fig. 8.1 shows that the power supply is a 9.0 V battery.

Fig. 8.1

Fig. 8.1

The current in the 450Ω450 \Omega resistor is 0.012 A .

State what is meant by electric current.

Question 2

[Maximum number: 1]

Fig. 10.1 shows an incomplete electrical circuit.

Fig. 10.1

Fig. 10.1

A student completes the circuit and measures the current in the 6.0Ω6.0 \Omega resistor.

On Fig. 10.1, draw an ammeter symbol in one gap and straight lines to indicate wires in the other gaps to show how the student should do this.

Question 3

[Maximum number: 5]

Fig. 6.1 shows an isolated metal sphere suspended by an insulating thread from the ceiling.

Fig. 6.1

Fig. 6.1

The sphere is negatively charged.

Question (a)

(a)

The magnitude of the charge on the sphere is 3.5×10−10C3.5 \times 10^{-10} \mathrm{C}.

An earthed metal wire is touched against the surface of the sphere and the sphere is discharged.

[ 5 ]

Question (i)

(i)

State what happens in the wire as the sphere is discharged.

[ 2 ]

Question (ii)

(ii)

It takes a time of 0.14 ns for the sphere to discharge completely.

Calculate the average current in the earthed wire as the sphere discharges.

[ 3 ]

Question 4

[Maximum number: 2]

Fig. 6.1 shows an isolated metal sphere suspended by an insulating thread from the ceiling.

Fig. 6.1

Fig. 6.1

The sphere is negatively charged.

The magnitude of the charge on the sphere is 3.5×10−10C3.5 \times 10^{-10} \mathrm{C}.

An earthed metal wire is touched against the surface of the sphere and the sphere is discharged.

State what happens in the wire as the sphere is discharged.

Question 5

[Maximum number: 1]

Which graph of voltage against time shows an a.c. voltage?

A
Figure for Question 5 — CAIE IGCSE Physics — Option A
B
Figure for Question 5 — CAIE IGCSE Physics — Option B
C
Figure for Question 5 — CAIE IGCSE Physics — Option C
D
Figure for Question 5 — CAIE IGCSE Physics — Option D

Question 6

[Maximum number: 2]

Fig. 7.1 shows two charged metal plates. X marks the position of the centre of the space between the plates.

Fig. 7.1

Fig. 7.1

During a thunderstorm, an electric field is set up between a cloud and the ground. Charges on the cloud and on the ground are shown in Fig. 7.2.

Fig. 7.2

Fig. 7.2

The lightning shown in Fig. 7.2 discharges a current of 28000 A for 0.0012 s .

Calculate the charge that flows from the cloud to the ground.

Question 7

[Maximum number: 2]

Fig. 9.1 shows a conducting ball that oscillates between two charged plates.

Fig. 9.1

Fig. 9.1

As the ball oscillates, it touches each plate in turn.

State which particles move when there is a current and state the direction in which they move through the sensitive ammeter.
particles:
direction:

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