Electricity & Magnetism MCQs with Answers

Metallic salts are classified as which of the following in terms of electrical conductivity?

• A.Conductors
• B.Insulators
• C.Semiconductors
• D.Superconductors

An electric cell of e.m.f E is connected across a copper wire of diameter d and length l. The drift velocity of electrons in the wire is vd. If the length of the wire is changed to 2l, the new drift velocity of electrons in the copper wire will be _?

• A.vd
• B.2 vd
• C.vd/2
• D.vd/4

Magnetic force acting on a charge at rest is?

• A.Maximum
• B.Zero
• C.Minimum but not zero
• D.Infinite

The cause of the potential barrier in a PN diode is ?

• A.Breakdown of the depletion region
• B.Excess electrons in the P-region
• C.Excess holes in the N-region
• D.Depletion of positive and negative charges near the junction

Past Paper MCQ

Which of the following is an example of a magnetic material?

• A.Iron
• B.Copper
• C.Aluminum
• D.Wood

An A.C emf of V=200 sin (10^t) volt is connected to a choke of negligible resistance. In order to produce current of amplitude I A, the inductance of choke should be _?

• A.20 H
• B.10 H
• C.200 H
• D.2 H

A charge of 90 C passes through a wire for 30 seconds. Then the current in the wire will be _?

• A.3 A
• B.30 A
• C.2700 A
• D.0.33 A

For measuring small resistance, we use ?

• A.Kelvin Bridge
• B.Wheatstone Bridge
• C.Post Office Box
• D.Megger

Lenz's law states that ?

• A.The magnitude of induced EMF is directly proportional to the rate of change of magnetic flux
• B.The induced current always flows in such a direction as to support the change which gives rise to it
• C.The induced current always flows in such a direction as to oppose the change which gives rise to it
• D.The induced current is independent of the direction of change in magnetic flux

Which of the following statement is true about the magnetic field inside a solenoid?

• A.It is perpendicular to the axis of the coil
• B.It is zero everywhere inside the solenoid
• C.It is along the axis of the coil
• D.It is circular around each turn of the coil