Physics for IGCSE & O level - Electricity (Section 3)
1
Which of the following components is found in a circuit and used to turn the circuit on and off?
Απάντηση
(C)
Switch
2
Which of the following is a good conductor of electricity?
Απάντηση
(C)
Copper
3
In a series circuit, if the resistance increases, what happens to the current?
Απάντηση
(B)
The current decreases.
4
What is the effect of temperature on the resistance of a semiconductor?
Απάντηση
(B)
Resistance decreases with increasing temperature.
5
If a 60W bulb and a 100W bulb are connected in parallel, which bulb will be brighter?
Απάντηση
(B)
The 100W bulb
6
In a parallel circuit, how is the total current related to the current through each branch?
Απάντηση
(C)
The total current is the sum of the currents in each branch.
7
Which of these appliances typically draws the highest current?
Απάντηση
(C)
An electric kettle
8
Which of these will increase the resistance of a wire?
Απάντηση
(D)
Increasing the length of the wire.
9
What is the relationship between power and current, given a constant voltage?
Απάντηση
(A)
Power is directly proportional to current.
10
Which of these devices is used to convert electrical energy into light?
Απάντηση
(C)
A light bulb
11
What is the difference between a series circuit and a parallel circuit in terms of current flow?
Απάντηση
(A)
Current is constant in a series circuit, but divides in a parallel circuit.
12
What component is used to convert electrical energy into light?
Απάντηση
(C)
Light bulb
13
In a parallel circuit with two resistors, if the current through one resistor is 2A and the current through the other is 3A, what is the total current supplied by the battery?
Απάντηση
(D)
5 A
14
What is the purpose of the neutral wire in a mains cable?
Απάντηση
(A)
To carry the current back to the source.
15
Which of these is a correct way of calculating voltage (V)?
Απάντηση
(B)
V = I * R
16
What type of current is supplied by a battery?
Απάντηση
(B)
DC
17
Which safety device is designed to open a circuit automatically when the current exceeds a certain value?
Απάντηση
(C)
Fuse
18
What is the effect on the resistance of a wire if you increase its cross-sectional area?
Απάντηση
(B)
Resistance decreases
19
What do conductors allow?
Απάντηση
(A)
Flow of electrons
20
What is measured in amperes?
Απάντηση
(B)
Current
21
If the voltage is constant, what happens to the current if the resistance increases?
Απάντηση
(B)
It decreases
22
What is the energy needed to move a unit charge between two points?
Απάντηση
(B)
Potential difference
23
What is the formula relating charge, current, and time?
Απάντηση
(B)
Charge = Current * Time
24
Which circuit arrangement is typically used for household wiring?
Απάντηση
(B)
Parallel
25
What is the total resistance of two 10-ohm resistors connected in series?
Απάντηση
(C)
20 ohms
26
What does the symbol on a lamp mean in a circuit diagram?
Απάντηση
(D)
A device that converts electrical energy into light
27
Which of the following components does NOT need an earth wire for safety?
Απάντηση
(D)
Double-insulated appliance
28
What are the two main types of electric circuits?
Απάντηση
(A)
Series and Parallel
29
What is the purpose of a switch in a circuit?
Απάντηση
(C)
To open or close the circuit
30
Which of these is the correct formula for calculating power (P)?
Απάντηση
(A)
P = V x I
31
What is the relationship between voltage (V), current (I), and resistance (R) in a circuit?
Απάντηση
(B)
V = I * R
32
What happens to the total power in a parallel circuit if one branch burns out?
Απάντηση
(B)
Decreases
33
What happens to the total resistance if two resistors are connected in series?
Απάντηση
(A)
The total resistance is the sum of the two resistors.
34
What is the formula for calculating power?
Απάντηση
(B)
P=V*I
35
Which part of a three-pin plug connects to the earth wire?
Απάντηση
(C)
The earth pin
36
What happens to the brightness of a lamp in a series circuit if the voltage of the battery is increased?
Απάντηση
(B)
Brightness increases
37
If two resistors (R1 and R2) are connected in parallel, and R1 = R2, what is the total resistance compared to either resistor?
Απάντηση
(C)
Half of either
38
What happens to the total power dissipated in a series circuit if you add more resistors?
Απάντηση
(A)
Increases
39
Which formula represents Ohm's law?
Απάντηση
(A)
V = I * R
40
What is the SI unit of electromotive force (EMF)?
Απάντηση
(B)
Volt
41
Which component is used to change AC voltage levels?
Απάντηση
(C)
Transformer
42
What type of current does a domestic electrical supply in many countries provide?
Απάντηση
(B)
Alternating Current (AC)
43
In a parallel circuit, if one branch opens (breaks the circuit), what happens to the other branches?
Απάντηση
(C)
The current in the other branches remains the same.
44
What does the fuse protect the electrical circuit against?
Απάντηση
(B)
Excess current
45
What happens to the total resistance of a circuit if more resistors are added in parallel?
Απάντηση
(B)
Decreases
46
How is the total resistance in a series circuit affected if one of the resistors is removed?
Απάντηση
(B)
Decreases
47
Which of the following is NOT a good conductor?
Απάντηση
(C)
Rubber
48
What is the name given to static electricity?
Απάντηση
(D)
electrostatic
49
Which is the formula relating power (P), current (I), and resistance (R)?
Απάντηση
(C)
P = I^2 * R
50
What is the total resistance of two resistors, one of 3 ohms and the other of 6 ohms, connected in parallel?
