Sign In

Physics for IGCSE & O level - Electricity (Section 4)

1
What is the purpose of the earth pin in a three-pin plug?
Answer
(A)
To provide a path for fault current.
2
What happens to the brightness of a light bulb if the current flowing through it decreases?
Answer
(B)
It gets dimmer
3
If a circuit has a voltage of 12V and a resistance of 4 ohms, what is the power dissipated?
Answer
(D)
16 W
4
What is the relationship between the resistance of a wire and its cross-sectional area?
Answer
(B)
Inversely proportional
5
In which direction does a the current flow?
Answer
(A)
Positive to negative
6
What does a fuse do in an electrical circuit?
Answer
(D)
It breaks the circuit if the current is too high
7
If two resistors, R1 and R2, are connected in parallel, and R1 is greater than R2, which of the following statements is true?
Answer
(B)
The voltage is the same across both.
8
What is the unit for electrical potential difference?
Answer
(B)
Volt
9
What do insulators prevent?
Answer
(A)
Flow of electrons
10
Which of the following is a semiconductor?
Answer
(C)
silicon
11
Which of the following would be a potential electrical hazard?
Answer
(B)
Touching a live wire.
12
What happens to the total current in a parallel circuit if one of the branches is opened (the circuit is broken in that branch)?
Answer
(B)
The total current decreases.
13
What is the effect of increasing the temperature of a metallic conductor on its resistance?
Answer
(A)
Resistance increases
14
What is the purpose of a variable resistor?
Answer
(C)
To control current flow
15
What is the formula relating power (P), current (I), and voltage (V)?
Answer
(B)
P = V * I
16
What happens to the current in a parallel circuit when a new branch is added?
Answer
(B)
The current increases
17
What is the approximate voltage of a standard UK mains supply?
Answer
(C)
230V
18
What is the unit used to measure electrical charge?
Answer
(D)
Coulomb
19
In a series circuit, what happens to the total resistance if you add another resistor?
Answer
(B)
Increases
20
If a 12V battery supplies current to a 4-ohm resistor, how much current flows through the resistor?
Answer
(A)
3A
21
If a 120V circuit has a 10-ohm resistor, what current flows through it?
Answer
(B)
12 A
22
If the voltage across a resistor doubles, and the resistance stays the same, what happens to the current?
Answer
(A)
It doubles.
23
In a parallel circuit with three resistors, if the current through each resistor is 1A, what is the total current flowing from the source?
Answer
(C)
3A
24
What type of circuit is typically used in a flashlight?
Answer
(A)
Series
25
What is the effect of increasing the temperature of a metallic wire?
Answer
(C)
The resistance increases.
26
How can you reduce the power consumption of an electrical appliance?
Answer
(D)
Decrease the voltage or current.
27
How are like charges affected?
Answer
(A)
They repel
28
What is the formula for calculating the total resistance of resistors in series?
Answer
(B)
R_total = R1 + R2
29
What does the term 'potential difference' refer to in an electrical circuit?
Answer
(C)
The force that pushes charges around a circuit.
30
What is the effect of adding more resistors in parallel on the total current supplied by the voltage source?
Answer
(B)
The total current increases.
31
What type of current is used by most battery-powered devices?
Answer
(B)
Direct Current (DC)
32
Which of the following is a good conductor of electricity?
Answer
(C)
Copper
33
Which of the following is a safety feature in a plug?
Answer
(C)
An earth wire
34
What kind of electrical devices can be connected in series?
Answer
(D)
All of the above
35
What is the voltage across a resistor if the current through it is 2 Amperes, and the resistance is 10 Ohms?
Answer
(C)
20V
36
What type of current flows in one direction only?
Answer
(B)
DC
37
Which of the following is an example of a semiconductor device?
Answer
(C)
A diode
38
In a parallel circuit, how is the voltage distributed?
Answer
(B)
It is the same across all components.
39
If the cross-sectional area of a wire is doubled, what happens to its resistance (assuming other factors are constant)?
Answer
(B)
Halves
40
What is the main difference between a live wire and a neutral wire?
Answer
(B)
The live wire is at a high voltage, while the neutral wire is at a low voltage (or close to zero).
41
What is the direction of electric current?
Answer
(B)
From positive to negative
42
In a parallel circuit, if one branch is opened (broken), what happens to the other branches?
Answer
(C)
The other branches continue to function normally.
43
What does the term 'short circuit' mean in an electrical context?
Answer
(B)
A circuit with a low resistance, often leading to excessive current.
44
What is the unit for potential difference?
Answer
(B)
Volt
45
What happens when two of the same charge are brought close together?
Answer
(B)
They repel each other
46
What is the effect on the resistance of a wire if its length is increased?
Answer
(B)
Resistance increases
47
What happens to the current in a circuit if the voltage is constant and the resistance increases?
Answer
(B)
The current decreases.
48
In a parallel circuit, what remains constant across all branches?
Answer
(A)
Voltage
49
Which component is designed to block the flow of current in one direction while allowing it in the other?
Answer
(C)
A diode
50
What type of circuit has only one path for current to flow?
Answer
(B)
Series