Free Electromagnetism MCQs with Answers

• A. F = qv(E+B)
• B. F = qE(v+B)
• C. F = qvB
• D. F = q(E+vB)

Explanation: Option D is correct since the Lorentz force refers specifically to the formula for the magnetic force, with the total electromagnetic…

• A. 8 times
• B. 2 times
• C. 4 times
• D. 16 times

Explanation: Magnetic Force = Centripetal Force. qvB = mv²/r so qB = mv/r. Therefore r can be written as r = mv/qB.

• A. 1 N
• B. 1.2 N
• C. 1.4 N
• D. 1.6 N

Explanation: Force due to a current element in a carrying conductor is given as F = ILB Where,'F' is the force'I' is the current'L' is the length of…

• A. Ammeter
• B. Voltmeter
• C. Resistance boxes
• D. All of these options are correct

Explanation: Non-inductive resistances are used in all of these.Inductive resistances can cause errors in the measurements made by ammeters…

• A. Attraction
• B. Replusive
• C. Retracting
• D. Opposing

Explanation: The force between two conductors with currents flowing in the same direction is attraction.

• A. Changing magnetic field in space
• B. Changing magnetic field in unit time
• C. Changing flux with space
• D. Constant magnetic field

Explanation: Motional emf is produced when a current-carrying conductor is moved in an external magnetic field.

• A. Self inductance only
• B. Mutual inductance
• C. Capacitive effect
• D. All of these options are correct

Explanation: This is a fact to be memorized. A transformer is based on the theory of mutual inductance. Hence, Option B is correct.

• A. Maximum magnetic flux
• B. Rate of change of magentic flux
• C. Change in magentic flux
• D. Initial flux

Explanation: Faraday's law states that the induced EMF is equal to the rate of change of magnetic flux. Hence, Option B is correct.

• A. Mechanical energy to heat energy
• B. Mechanical energy to electrical energy
• C. Electrical energy to mechanical energy
• D. Heat energy to electrical energy

Explanation: A generator can convert mechanical/kinetic energy to electrical energy. It can produce either AC or DC current.

• A. Genghis Khan
• B. Lenz
• C. Isaac Newton
• D. Michael Faraday

Explanation: Michael Faraday introduced the law of electromagnetic induction. Faraday's law of electromagnetic induction states that a current is…

• A. QvBl
• B. None of these
• C. QvB cosθ
• D. QvB sinθ

Explanation: When a charge moves through a magnetic field, a force is applied on it which is given by:F = QvB sinθQvBl is the motional EMF produced…

• A. Wbm-1
• B. Wbm-2
• C. Wbm2
• D. Wb

Explanation: Wbm-2: This option suggests that magnetic field strength is measured in Wbm-2.

• A. IL sinϴ
• B. ILB
• C. IL
• D. IB sinϴ

Explanation: IB sinϴ: This option suggests that the force on a current-carrying conductor per unit length is given by IB sinϴ.

• A. It moves towards solenoid and rotates through 180˚
• B. It moves towards the solenoid
• C. It moves away from solenoid
• D. It moves away from solenoid and rotates through 180˚

Explanation: According to the right-hand grip rule, a north pole is induced at the end of the solenoid which faces the south pole of the magnet.

• A. 4π x 10-13 tesla
• B. 4π x 10-17 tesla
• C. 4π x 10-10 tesla
• D. 4π x 10-16tesla

Explanation: Given that,Length = L= 10cm which is 0.1mNumber of turns = n = 100Current passed = 1μ which is 1 x 10-6AUsing the formula for magnetic…

• A. Magnetic field at 'X' is stronger than that at 'Y' and 'Z'
• B. Magnetic field at 'X' is weaker than that at 'Y' and 'Z'
• C. Magnetic field at 'X', 'Y' and 'Z' is same
• D. Magnetic field at 'X' is weaker than that at 'Y' but stronger than that at 'Z'.
• E. Magnetic field at 'Y' is stronger than that at 'X' and 'Z'

Explanation: When two parallel wires carry equal and opposite currents, they create a magnetic field around them.

• A. Audio generator
• B. Time base generator
• C. Signal generator
• D. Linear generator

Explanation: The circuit that provides voltage to X-plates is called a "time base generator".

• A. Voltage is connected to X input and the time base is switched off
• B. Voltage is connected to Y input and the time base is switched on
• C. Voltage is connected to Y input and the time base is switched off
• D. Voltage is connected to X input and the time base is switched on

Explanation: Voltage should be connected to Y and time base switched on.

• A. Filament, cathode, grid, anodes
• B. Cathode, anode, capacitor, screen
• C. Emitter, base, collector
• D. Resistance, capacitor, inductor

Explanation: The beam of the electrons is provided by an electron gun which consists of an indirectly heated cathode, a grid and three anodes.

• A. Both carry current in same direction
• B. Both carry current in opposite direction
• C. Wire 1 has current, but Wire 2 has no current
• D. Wire 2 has current, Wire 1 has no current

Explanation: Two parallel wires have currents travelling in opposite directions, the magnetic fields generated by those currents between the wires will…