Online Test — Electricity — Circuits and Effects
25 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 25
Electric current is the flow of:
Heat
Electric charge
Light
Sound
Explanation: Electric current is the flow of electric charge (electrons).
Question 2 of 25
The SI unit of electric current is the:
Volt
Ampere
Ohm
Watt
Explanation: The SI unit of current is the ampere (A).
Question 3 of 25
Conventional current flows from the ______ terminal to the ______ terminal.
Negative; positive
Positive; negative
Top; bottom
Left; right
Explanation: By convention, current flows from the positive to the negative terminal.
Question 4 of 25
Potential difference is given by the formula:
V = W/Q
V = IR only
V = mg
V = F/A
Explanation: Potential difference is the work done per unit charge, V = W/Q.
Question 5 of 25
Potential difference (voltage) is measured with a:
Ammeter
Voltmeter
Thermometer
Barometer
Explanation: A voltmeter measures potential difference (in volts).
Question 6 of 25
Ohm's law is expressed by the formula:
V = IR
P = VI
Q = mcΔT
F = ma
Explanation: Ohm's law states V = IR.
Question 7 of 25
The opposition offered by a conductor to the flow of current is called:
Voltage
Current
Resistance
Power
Explanation: Resistance is the opposition to the flow of current.
Question 8 of 25
The SI unit of resistance is the:
Volt
Ampere
Ohm
Watt
Explanation: The SI unit of resistance is the ohm (Ω).
Question 9 of 25
If 12 V is applied across a 3 Ω resistor, the current is:
4 A
9 A
36 A
15 A
Explanation: I = V/R = 12 ÷ 3 = 4 A.
Question 10 of 25
A longer wire (other factors same) has ______ resistance.
Less
More
Zero
The same
Explanation: A longer wire offers more resistance to current.
Question 11 of 25
In a series circuit, the current through each component is:
Different
The same
Zero
Doubled
Explanation: A series circuit has one path, so the same current flows through each component.
Question 12 of 25
In a series circuit, the total resistance is found by:
Adding the resistances
Subtracting them
Dividing them
1/R = 1/R₁ + 1/R₂
Explanation: In series, R = R₁ + R₂ + … (resistances add).
Question 13 of 25
Two resistors of 4 Ω and 6 Ω in series have a total resistance of:
2 Ω
10 Ω
24 Ω
2.4 Ω
Explanation: In series, R = 4 + 6 = 10 Ω.
Question 14 of 25
In a parallel circuit, the voltage across each branch is:
Different
The same
Zero
Always increasing
Explanation: In parallel, the voltage across each branch is the same (the source voltage).
Question 15 of 25
Household appliances are connected in parallel so that:
All stop if one fails
Each gets full voltage and works independently
The voltage is shared
Resistance increases
Explanation: In parallel, each appliance gets full voltage and works independently.
Question 16 of 25
Electric power is the rate at which electrical energy is:
Stored
Used
Created
Destroyed
Explanation: Power is the rate at which electrical energy is used (energy per second).
Question 17 of 25
The SI unit of electric power is the:
Volt
Ampere
Watt
Ohm
Explanation: The SI unit of power is the watt (W).
Question 18 of 25
Which of these is a correct formula for electric power?
P = VI
P = V/I only
P = V + I
P = IR
Explanation: Electric power is P = VI (also I²R and V²/R).
Question 19 of 25
One kilowatt-hour (1 unit) is the energy used by a 1 kW appliance in:
1 second
1 minute
1 hour
1 day
Explanation: 1 kWh is the energy used by a 1 kW appliance in 1 hour.
Question 20 of 25
A 2 kW heater used for 3 hours consumes:
2 units
3 units
6 units
5 units
Explanation: Energy = power × time = 2 × 3 = 6 kWh = 6 units.
Question 21 of 25
The heat produced when current flows through a resistance is given by:
H = I²Rt
V = IR
P = mgh
Q = mcΔT
Explanation: The heating effect (Joule's heating) gives H = I²Rt.
Question 22 of 25
A fuse protects a circuit by:
Increasing the current
Melting and breaking the circuit if current is too large
Storing charge
Producing light
Explanation: A fuse melts and breaks the circuit when too large a current flows.
Question 23 of 25
The wire that carries current at high voltage in a domestic circuit is the:
Earth wire
Neutral wire
Live wire
Fuse wire
Explanation: The live wire carries the current at high voltage.
Question 24 of 25
Connecting an appliance's metal body to the earth wire is called:
Short circuit
Earthing
Overloading
Insulating
Explanation: Earthing connects the metal body to the ground to prevent shocks.
Question 25 of 25
A short circuit occurs when the live and neutral wires:
Are far apart
Touch directly
Are switched off
Are earthed
Explanation: A short circuit is when live and neutral wires touch directly, causing a large current.