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WorksheetsElectricity & D.C. Circuits (Topic test)
Total questions: 25
Worksheet time: 1hrs 20mins
The potential difference V across a filament lamp is slowly raised from zero to its normal operating value. Which graph represents the variation with V of the current I in the lamp?
A
B
C
D
Two lamps are connected in series to a 250V power supply. One lamp is rated 240V, 60W and the other is rated 10V, 2.5W. Which statement most accurately describes what happens?
Both lamps light at less than their normal brightness.
Both lamps light at their normal brightness.
Only the 240V lamp lights.
The 10V lamp blows.
Which equation is used to define resistance?
energy = (current)2 × resistance × time
potential difference = current × resistance
power = (current)2 × resistance
resistivity = resistance × area ÷ length
The charge that a fully charged 12V car battery can supply is 100kC. The starter motor of the car requires a current of 200A for an average period of 2.0 s. The battery does not recharge because of a fault. What is the maximum number of times the starter motor of the car can be used?
21
25
42
250
A potential divider circuit is formed by connecting a battery of negligible internal resistance in series with two variable resistors, as shown.
(see image)
The variable resistors have resistances RX and RY.
VX is the potential difference across resistance RX.
RX and RY are both changed at the same time.
Which combination of changes must cause VX to increase?
RX larger, RY larger
RX larger, RY smaller
RX smaller, RY larger
RX smaller, RY smaller
In the circuit shown, contact may be made at any point along the 3Ω resistor (potentiometer).
(see image)
The battery has e.m.f. 9V and negligible internal resistance. What is the maximum range of the output voltage?
0 - 2 V
0 - 5 V
2 - 3 V
2 - 5 V
The diagram shows a junction in a circuit where three wires P, Q and R meet. The currents in P and Q are 1A and 3A respectively, in the directions shown.
(see image)
How much charge passes a given point in wire R in a time of 5s?
0.4 C
2 C
10 C
20 C
A wire carries a current of 2.0A for 1.0 hour. How many electrons pass a point in the wire in this time?
1.2 × 10–15
7.2 × 103
1.3 × 1019
4.5 × 1022
The diagram shows an electric circuit in which the resistance of the external resistor is 2R and the internal resistance of the source is R.
(see image)
What is the ratio :
(power in internal resistance) / (power in external resistor) ?
1/4
1/2
2
4
The graph shows the variation with potential difference V of the current I in components X, Y and Z.
(see image)
Which row correctly identifies the components?
X is a metallic conductor at constant temperature; Z is a semiconductor diode; Y is a filament lamp
Y is a metallic conductor at constant temperature; X is a semiconductor diode; Z is a filament lamp
Y is a metallic conductor at constant temperature; Z is a semiconductor diode; X is a filament lamp
Z is a metallic conductor at constant temperature; Y is a semiconductor diode; X is a filament lamp
Four statements about either potential difference or electromotive force are listed.
1) It involves changing electrical energy into other forms.
2) It involves changing other energy forms into electrical energy.
3) It is the energy per unit charge to move charge around a complete circuit.
4) It is the work done per unit charge by the charge moving from one point to another.
Which statements apply to potential difference?
1 and 4
2 and 3
1 only
3 only
In the circuit shown, there is a current of 3.0A in the 2.0Ω resistor.
(see below)
What are the values of the current I delivered by the power supply and the voltage V across it?
I = 3.0 A, V = 10.5 V
I = 4.0 A, V = 9.0 V
I = 4.0 A, V = 12 V
I = 12 A, V = 18 V
Free electrons flow along a copper wire X of radius 5.0x10–5 m with an average drift speed of 2.8x10–2 ms–1. The current in the wire is 3.0 A.
There is a current of 2.0 A in a copper wire Y of radius 1.0x10–4 m.
What is the average drift speed of the free electrons in copper wire Y?
4.7 x 10–3 ms–1
9.3 x 10–3 ms–1
1.1 x 10–2 ms–1
1.9 x 10–2 ms–1
What is the definition of potential difference?
power per unit current
product of current and resistance
product of electric field strength and distance
work done per unit charge
A cable of length L consisting of two wires is used to connect a 12.0 V power supply of negligible internal resistance to a lamp, as shown.
(see image)
The potential difference across the lamp is 10.5 V. The current in the wire is 2.50 A. Each wire is made of metal of resistivity 1.70 x 10–8 m and has a cross-sectional area of 6.00 x 10–7 m2 .
What is the length L of the cable?
10.6 m
21.2 m
29.4 m
58.8 m
The unit of electric charge is the coulomb.
What is meant by 1 coulomb?
the charge passing a point in 1 second when a current produces 1 joule of work
the charge passing a point in 1 second when a current produces 1 watt of power
the charge passing a point in 1 second when there is a current of 1 ampere
the charge passing a point in 1 second when there is 1 ohm of resistance
Two copper wires are joined together and carry a current, as shown.
(see image)
Wire P has diameter d and wire Q has diameter 2d.
What is the ratio:
(average drift speed of the free electrons in wire P)/(average drift speed of the free electrons in wire Q) ?
1/4
1/2
2
4
A power supply of electromotive force (e.m.f.) V and negligible internal resistance is connected in the circuit shown. There is a current of 3.0A in the 4.0Ω resistor.
(see image)
What is the value of V?
15 V
29 V
39 V
51 V
The wire of a heating element has resistance R. The wire breaks and is replaced by a different wire.
Data for the original wire and for the replacement wire are shown in the table. (see image)
What is the resistance of the replacement wire?
R/4
R/2
R
2R
A filament lamp has a resistance of 180 Ω when the current in it is 500 mA.
What is the power transformed in the lamp?
45 W
50 W
90 W
1400 W
A 12V battery is in series with an ammeter, a 2Ω fixed resistor and a 0–10Ω variable resistor. High-resistance voltmeters P and Q are connected across the variable resistor and the fixed resistor respectively, as shown.
(see image)
The resistance of the variable resistor is changed from its maximum value to zero. Which graph shows the variation with current of the voltmeter readings?
(see options on image)
A
B
C
D
Five resistors are connected as shown.
(see image)
What is the total resistance between P and Q?
0.25 Ω
0.61 Ω
4.0 Ω
16 Ω
A light-dependent resistor (LDR) is connected in series with a resistor R and a battery.
(see image)
The resistance of the LDR is equal to the resistance of R when no light falls on the LDR.
When the light intensity falling on the LDR increases, which statement is correct?
The current in R decreases.
The current in the LDR decreases.
The p.d. across R decreases.
The p.d. across the LDR decreases.
A metal wire of length 0.50 m has a resistance of 12 Ω.
What is the resistance of a wire of length 2.0 m and made of the same material, but with half the
diameter?
12 Ω
48 Ω
96 Ω
192 Ω
A pedal bicycle is fitted with an electric motor. The rider switches on the motor for a time of 3.0 minutes. A constant current of 3.5 A in the electric motor is provided from a battery with a terminal voltage of 24 V.
What is the energy supplied by the battery?
84 J
250 J
650 J
15 000 J
