The diagram shows the symbol for a wire carrying a current I.
What does this current represent?
A the amount of charge flowing past a point in XY per second
B the number of electrons flowing past a point in XY per second
C the number of positive ions flowing past a point in XY per second
D the number of protons flowing past a point in XY per second
Which amount of charge, flowing in the given time, will produce the largest current?
A
B
C
D
A 12 V battery is charged for 20 minutes by connecting it to a source of electromotive force (e.m.f.). The battery is supplied with 7.2 × 104 J of energy in this time.
How much charge flows into the battery?
A 5.0 C
B 60 C
C 100 C
D 6000 C
A particle has a charge of 4.8 × 10–19 C. The particle remains at rest between a pair of horizontal, parallel plates having a separation of 15 mm. The potential difference between the plates is 660 V.
What is the weight of the particle?
A 2.1 × 10^−14 N
B 2.1 × 10^−15 N
C 2.1 × 10^−17 N
D 1.1 × 10^−23 N
Three cells with e.m.f.s V1, V2 and V3, have negligible internal resistance. These cells are connected to three resistors with resistances R1, R2 and R3, as shown. The current in the circuit is I.
Which equation is correct?
Three resistors, each of resistance R, are connected in a network, as shown. The total resistance between points X and Y is 8.0 Ω.
What is the value of R ?
A 2.7 Ω
B 4.0 Ω
C 5.3 Ω
D 12 Ω
The battery of a car has an internal resistance of 0.10 Ω and an electromotive force of 12 V. When the battery is connected to the starter motor, the potential difference across the battery terminals is 7.0 V.
What is the current supplied to the starter motor?
A 50 A
B 70 A
C 120 A
D 190 A
A wire RST is connected to another wire XY as shown. Each wire is 100 cm long with a resistance per unit length of 10 Ω.m–1.
What is the total resistance between X and Y?
A 3.3 Ω
B 5.0 Ω
C 8.3 Ω
D 13.3 Ω
A pencil is used to draw a line of length 30 cm and width 1.2 mm. The resistivity of the material in the pencil is 2.0 × 10–5 Ω m and the resistance of the line is 40 kΩ.
What is the thickness of the line?
A 1.25 × 10^–10 m
B 1.25 × 10^–8 m
C 1.25 × 10^–7 m
D 1.25 × 10^–5 m
The diagram shows a low-voltage circuit for heating the water in a fish tank. The heater has a resistance of 3.0 Ω. The voltage source has an e.m.f. of 12 V and an internal resistance of 1.0 Ω.
At what rate does the voltage source supply energy to the heater?
A 27 W
B 36 W
C 48 W
D 64 W
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