Vidaara.orgClass 8 · Mathematics
CodeVID-M8-WS
Electricity — Circuits and Effects — Practice Worksheet
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Choose the correct option (A, B, C or D) for each question.
- The answer key is at the end — try the paper first!
Section A — Multiple Choice (1 mark each)
25 × 1 = 25 marks
1.
Electric current is the flow of:
- A.Heat
- B.Electric charge
- C.Light
- D.Sound
2.
The SI unit of electric current is the:
- A.Volt
- B.Ampere
- C.Ohm
- D.Watt
3.
Conventional current flows from the ______ terminal to the ______ terminal.
- A.Negative; positive
- B.Positive; negative
- C.Top; bottom
- D.Left; right
4.
Potential difference is given by the formula:
- A.V = W/Q
- B.V = IR only
- C.V = mg
- D.V = F/A
5.
Potential difference (voltage) is measured with a:
- A.Ammeter
- B.Voltmeter
- C.Thermometer
- D.Barometer
6.
Ohm's law is expressed by the formula:
- A.V = IR
- B.P = VI
- C.Q = mcΔT
- D.F = ma
7.
The opposition offered by a conductor to the flow of current is called:
- A.Voltage
- B.Current
- C.Resistance
- D.Power
8.
The SI unit of resistance is the:
- A.Volt
- B.Ampere
- C.Ohm
- D.Watt
9.
If 12 V is applied across a 3 Ω resistor, the current is:
- A.4 A
- B.9 A
- C.36 A
- D.15 A
10.
A longer wire (other factors same) has ______ resistance.
- A.Less
- B.More
- C.Zero
- D.The same
11.
In a series circuit, the current through each component is:
- A.Different
- B.The same
- C.Zero
- D.Doubled
12.
In a series circuit, the total resistance is found by:
- A.Adding the resistances
- B.Subtracting them
- C.Dividing them
- D.1/R = 1/R₁ + 1/R₂
13.
Two resistors of 4 Ω and 6 Ω in series have a total resistance of:
- A.2 Ω
- B.10 Ω
- C.24 Ω
- D.2.4 Ω
14.
In a parallel circuit, the voltage across each branch is:
- A.Different
- B.The same
- C.Zero
- D.Always increasing
15.
Household appliances are connected in parallel so that:
- A.All stop if one fails
- B.Each gets full voltage and works independently
- C.The voltage is shared
- D.Resistance increases
16.
Electric power is the rate at which electrical energy is:
- A.Stored
- B.Used
- C.Created
- D.Destroyed
17.
The SI unit of electric power is the:
- A.Volt
- B.Ampere
- C.Watt
- D.Ohm
18.
Which of these is a correct formula for electric power?
- A.P = VI
- B.P = V/I only
- C.P = V + I
- D.P = IR
19.
One kilowatt-hour (1 unit) is the energy used by a 1 kW appliance in:
- A.1 second
- B.1 minute
- C.1 hour
- D.1 day
20.
A 2 kW heater used for 3 hours consumes:
- A.2 units
- B.3 units
- C.6 units
- D.5 units
21.
The heat produced when current flows through a resistance is given by:
- A.H = I²Rt
- B.V = IR
- C.P = mgh
- D.Q = mcΔT
22.
A fuse protects a circuit by:
- A.Increasing the current
- B.Melting and breaking the circuit if current is too large
- C.Storing charge
- D.Producing light
23.
The wire that carries current at high voltage in a domestic circuit is the:
- A.Earth wire
- B.Neutral wire
- C.Live wire
- D.Fuse wire
24.
Connecting an appliance's metal body to the earth wire is called:
- A.Short circuit
- B.Earthing
- C.Overloading
- D.Insulating
25.
A short circuit occurs when the live and neutral wires:
- A.Are far apart
- B.Touch directly
- C.Are switched off
- D.Are earthed
Answer Key
Section A — Multiple Choice (1 mark each)
- (B) Electric charge
- (B) Ampere
- (B) Positive; negative
- (A) V = W/Q
- (B) Voltmeter
- (A) V = IR
- (C) Resistance
- (C) Ohm
- (A) 4 A
- (B) More
- (B) The same
- (A) Adding the resistances
- (B) 10 Ω
- (B) The same
- (B) Each gets full voltage and works independently
- (B) Used
- (C) Watt
- (A) P = VI
- (C) 1 hour
- (C) 6 units
- (A) H = I²Rt
- (B) Melting and breaking the circuit if current is too large
- (C) Live wire
- (B) Earthing
- (B) Touch directly
Generated by Vidaara.org · Assignment VID-M8-WS · vidaara.org