Physics for IGCSE & O level - Electricity (Section 4)
1
What is the purpose of the earth pin in a three-pin plug?
คำตอบ(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?
3
If a circuit has a voltage of 12V and a resistance of 4 ohms, what is the power dissipated?
4
What is the relationship between the resistance of a wire and its cross-sectional area?
5
In which direction does a the current flow?
6
What does a fuse do in an electrical circuit?
คำตอบ(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?
คำตอบ(B)
The voltage is the same across both.
8
What is the unit for electrical potential difference?
9
What do insulators prevent?
10
Which of the following is a semiconductor?
11
Which of the following would be a potential electrical hazard?
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)?
คำตอบ(B)
The total current decreases.
13
What is the effect of increasing the temperature of a metallic conductor on its resistance?
14
What is the purpose of a variable resistor?
15
What is the formula relating power (P), current (I), and voltage (V)?
16
What happens to the current in a parallel circuit when a new branch is added?
17
What is the approximate voltage of a standard UK mains supply?
18
What is the unit used to measure electrical charge?
19
In a series circuit, what happens to the total resistance if you add another resistor?
20
If a 12V battery supplies current to a 4-ohm resistor, how much current flows through the resistor?
21
If a 120V circuit has a 10-ohm resistor, what current flows through it?
22
If the voltage across a resistor doubles, and the resistance stays the same, what happens to the current?
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?
24
What type of circuit is typically used in a flashlight?
25
What is the effect of increasing the temperature of a metallic wire?
คำตอบ(C)
The resistance increases.
26
How can you reduce the power consumption of an electrical appliance?
คำตอบ(D)
Decrease the voltage or current.
27
How are like charges affected?
28
What is the formula for calculating the total resistance of resistors in series?
29
What does the term 'potential difference' refer to in an electrical circuit?
คำตอบ(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?
คำตอบ(B)
The total current increases.
31
What type of current is used by most battery-powered devices?
32
Which of the following is a good conductor of electricity?
33
Which of the following is a safety feature in a plug?
34
What kind of electrical devices can be connected in series?
35
What is the voltage across a resistor if the current through it is 2 Amperes, and the resistance is 10 Ohms?
36
What type of current flows in one direction only?
37
Which of the following is an example of a semiconductor device?
38
In a parallel circuit, how is the voltage distributed?
คำตอบ(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)?
40
What is the main difference between a live wire and a neutral wire?
คำตอบ(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?
คำตอบ(B)
From positive to negative
42
In a parallel circuit, if one branch is opened (broken), what happens to the other branches?
คำตอบ(C)
The other branches continue to function normally.
43
What does the term 'short circuit' mean in an electrical context?
คำตอบ(B)
A circuit with a low resistance, often leading to excessive current.
44
What is the unit for potential difference?
45
What happens when two of the same charge are brought close together?
46
What is the effect on the resistance of a wire if its length is increased?
47
What happens to the current in a circuit if the voltage is constant and the resistance increases?
48
In a parallel circuit, what remains constant across all branches?
49
Which component is designed to block the flow of current in one direction while allowing it in the other?
50
What type of circuit has only one path for current to flow?
