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Physics for IGCSE & O level - Electricity (Section 7)

1
What is the role of the lamp in a circuit?
Answer
(C)
To convert electrical energy to light and heat
2
What is the role of a fuse in an electrical circuit?
Answer
(B)
To prevent overcurrent.
3
In a series circuit, what is constant across all components?
Answer
(B)
Current
4
In a parallel circuit, how does the total current compare to the sum of the currents in each branch?
Answer
(C)
The total current is greater.
5
What is the value of 1 mA (milliampere) in amperes?
Answer
(C)
0.001 A
6
What is the standard voltage for the main electrical supply in the UK?
Answer
(C)
230 V
7
What type of device can be used to measure the voltage of a circuit?
Answer
(B)
Voltmeter
8
What happens to the resistance of a thermistor if the temperature increases?
Answer
(B)
Resistance decreases
9
If the voltage across a resistor is doubled, and the resistance stays the same, what happens to the power dissipated by the resistor?
Answer
(C)
The power is quadrupled.
10
What is the relationship between current and resistance?
Answer
(B)
They are inversely proportional.
11
Which type of circuit provides multiple paths for current to flow?
Answer
(B)
Parallel circuit
12
What are the units of current?
Answer
(C)
Amperes
13
Which component can be used to vary the current in a circuit?
Answer
(C)
A variable resistor (potentiometer)
14
If you double the voltage in a circuit and the resistance remains constant, how does the current change?
Answer
(B)
Doubles
15
Which of the following factors will increase the resistance of a wire?
Answer
(D)
Increasing the length
16
What happens to the total resistance when resistors are connected in parallel?
Answer
(B)
Decreases
17
If you connect a series circuit with a 10-ohm resistor, a 20-ohm resistor, and a 30-ohm resistor, what is the total resistance?
Answer
(D)
60 ohms
18
What are the correct equations related to calculating electrical energy?
Answer
(A)
Energy transformed = Power x Time
19
What is the effect of connecting several cells in series?
Answer
(A)
The voltage increases.
20
What is the relationship between the current and the resistance in a circuit, assuming a constant voltage?
Answer
(B)
Inversely proportional
21
What do series circuits and parallel circuits have in common?
Answer
(C)
They both can include resistors.
22
What is the purpose of a rectifier in an electrical circuit?
Answer
(B)
To convert AC to DC
23
Which of the following components can be found in a potential divider?
Answer
(B)
A variable resistor
24
What does the term "p.d." stand for in electrical circuits?
Answer
(B)
Potential Difference
25
Which property of a material opposes the flow of electric current?
Answer
(C)
Resistance
26
What is the conventional current direction in a circuit?
Answer
(B)
From positive to negative terminal of battery.
27
What happens if one bulb burns out in a parallel circuit?
Answer
(C)
The other bulbs stay lit.
28
Which of the following is NOT a factor affecting resistance?
Answer
(C)
The color of the conductor
29
In a household electrical circuit, what does the 'neutral' wire provide?
Answer
(A)
The return path for the current
30
If the length of a wire is doubled, and all other factors remain the same, what happens to the resistance?
Answer
(A)
The resistance doubles
31
What does a diode allow current to flow in?
Answer
(B)
One direction only
32
What is the function of a diode?
Answer
(B)
To allow current to flow in one direction only
33
What is the relationship between voltage, current, and resistance in a circuit?
Answer
(A)
Ohm's Law describes this relationship.
34
What is the purpose of a three-pin plug?
Answer
(B)
To connect the appliance to the earth
35
If a wire is made of a material with high resistivity, how does it affect resistance?
Answer
(A)
Increases resistance
36
What is the purpose of the earth (grounded) wire?
Answer
(C)
To provide a low-resistance path to the ground in case of a fault.
37
In a UK plug, which pin is the longest and is connected to the earth?
Answer
(C)
The earth pin
38
In a parallel circuit, what is the relationship between voltage across each branch?
Answer
(B)
Voltage is the same across all branches
39
Which of the following is a component in a simple circuit?
Answer
(D)
All the above
40
Which device is designed to open a circuit if a fault current is detected?
Answer
(C)
An RCD
41
In an electrical circuit, what does a resistor do?
Answer
(B)
Reduces the flow of current
42
What happens to the resistance of a wire as its length increases?
Answer
(B)
Resistance increases.
43
What are the advantages of a parallel circuit?
Answer
A
C
44
What is the difference between a conductor and an insulator?
Answer
(C)
Conductors allow current to flow easily, insulators resist it.
45
What kind of charge does a proton have?
Answer
(A)
Positive
46
How do you calculate the total resistance of resistors connected in series?
Answer
(C)
Sum the individual resistances
47
What type of current does a transformer usually work with?
Answer
(B)
Alternating Current
48
What is the unit for potential difference (p.d.)?
Answer
(B)
Volt
49
Which of the following is an example of a non-ohmic conductor?
Answer
(C)
A diode
50
If the voltage in a circuit is doubled and the resistance remains the same, what happens to the power?
Answer
(C)
The power increases by a factor of four