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Physics for IGCSE & O level - Electricity (Section 8)

1
What does the 'live' wire do in an electrical circuit?
Answer
(B)
Carries the current from the source
2
What is the unit of measurement for electrical potential difference (voltage)?
Answer
(B)
Volt
3
What unit is commonly used to measure the frequency of AC electricity?
Answer
(C)
Hertz
4
What are the basic components of an electrical circuit?
Answer
A
B
C
5
What is the formula for calculating power (P) using voltage (V) and current (I)?
Answer
(C)
P = V * I
6
What unit is used to measure potential difference?
Answer
(B)
Volt
7
Which of the following components is designed to limit current?
Answer
(B)
Resistor
8
Which of the following is a property of parallel circuits?
Answer
(B)
Voltage is the same across all components
9
What happens to the current if the voltage is kept constant, and the resistance is halved?
Answer
(B)
The current is doubled.
10
What is the unit of measurement for electrical resistance?
Answer
(C)
Ohm
11
If the length of a wire is reduced to a quarter of its original length, how does the resistance change?
Answer
(B)
Decreases to a quarter
12
What happens to the brightness of a lamp if the current flowing through it increases?
Answer
(C)
It becomes brighter
13
In a series circuit, what happens to the voltage drop across each resistor?
Answer
(B)
The voltage drop is proportional to the resistance.
14
What is the combined resistance of resistors in series?
Answer
(A)
R1 + R2
15
What is the purpose of a fuse in an electrical circuit?
Answer
(C)
To protect the circuit from overcurrent.
16
What does the term 'current' refer to in an electrical circuit?
Answer
(B)
The rate of flow of electric charge
17
Which of the following can be charged by rubbing?
Answer
(C)
Polythem
18
What type of electrical current flows in one direction only?
Answer
(B)
Direct current
19
What is the relationship between voltage, current, and resistance (Ohm's Law)?
Answer
(C)
Voltage is directly proportional to both current and resistance
20
If the current is kept constant, how does doubling the resistance affect the voltage?
Answer
(B)
The voltage is doubled.
21
Which unit measures the rate of electrical energy transfer?
Answer
(D)
Watt
22
What is the SI unit for power?
Answer
(C)
Watt
23
If the voltage across a 4-ohm resistor is 12 volts, what is the current flowing through it?
Answer
(A)
3 amps
24
What is the purpose of a ground wire in an electrical circuit?
Answer
(B)
To protect against electric shock.
25
What type of circuit has all of its components connected along a single path?
Answer
(B)
Series Circuit
26
If a copper wire has twice the diameter of another copper wire, what is the relationship between their resistances?
Answer
(A)
The resistance of the wider wire is half.
27
What materials are used in electrostatic precipitators?
Answer
A
C
28
Which statement is true about the current in a series circuit?
Answer
(C)
The current is the same at all points.
29
Which of the following can cause an object to be charged?
Answer
(D)
All of the above
30
What does a voltmeter measure?
Answer
(B)
Voltage (Potential Difference)
31
If two resistors are connected in series and have values of 10 ohms and 20 ohms, what is the total resistance?
Answer
(C)
30 ohms
32
What is the purpose of a potential divider?
Answer
(B)
To divide the voltage
33
What is the unit for resistance?
Answer
(C)
Ohm
34
What is the formula for calculating power (P) given voltage (V) and current (I)?
Answer
(B)
P = V * I
35
What component is used to increase or decrease AC voltage?
Answer
(C)
Transformer
36
What are the units used to measure electrical resistance?
Answer
(C)
Ohms
37
What is the difference between a series and a parallel circuit?
Answer
(A)
Only one path for the current flow vs multiple paths
38
If a 100W light bulb operates at 120V, what is the current draw?
Answer
(A)
0.83 Amps
39
If the resistance in a circuit is increased and the voltage remains constant, what happens to the current?
Answer
(B)
It decreases
40
What can a charged object do to an uncharged object?
Answer
(B)
Attract it
41
What are the dangers of touching electrical wires?
Answer
A
B
C
42
What is the relationship between voltage and current in a circuit, according to Ohm's law?
Answer
(A)
Directly proportional
43
If a 10-ohm resistor and a 20-ohm resistor are connected in parallel, which statement is correct?
Answer
(B)
The current through the 20-ohm resistor is less.
44
What is the name of the part of atom with negative charge?
Answer
(C)
Electron
45
Which of these is a common use for a reed switch?
Answer
(B)
Detecting the presence of a magnet
46
What charge is associated with the neutrons?
Answer
(C)
Neutral
47
What are the advantages of using a parallel circuit?
Answer
A
B
48
What is the role of a step-up transformer?
Answer
(B)
To increase the voltage
49
Which component in an electrical circuit converts electrical energy into light energy?
Answer
(C)
Light bulb
50
What happens if you reverse the terminals of a diode in a circuit?
Answer
(B)
No current will flow.