Question 1

What is the SI unit of electric current?

Accepted Answer

Electric current is the flow of charge per unit time, and its SI unit is Ampere (A), where 1 A = 1 Coulomb/second.

Question 2

A wire of resistance 10 Ω carries a current of 2 A. What is the potential difference across the wire?

Accepted Answer

Using Ohm's Law (V = IR), potential difference = 10 Ω × 2 A = 20 V.

Question 3

Which of the following materials is the best conductor of electricity?

Accepted Answer

Copper has very low electrical resistance and is one of the best electrical conductors, commonly used in wiring and circuits.

Question 4

What is the direction of the magnetic field around a straight current-carrying wire?

Accepted Answer

By the right-hand rule, the magnetic field around a current-carrying wire forms concentric circles in a plane perpendicular to the wire.

Question 5

A wire of length 2 m carries a current of 5 A in a magnetic field of 0.5 T perpendicular to the wire. What is the force experienced by the wire?

Accepted Answer

Using the formula F = BIL, where B = 0.5 T, I = 5 A, and L = 2 m, we get F = 0.5 × 5 × 2 = 5 N.

Question 6

Which of the following is the SI unit of magnetic flux density?

Accepted Answer

Tesla (T) is the SI unit of magnetic flux density, where 1 T = 1 Wb/m².

Question 7

Two identical bar magnets are placed with their north poles facing each other at a distance of 5 cm. What force will be observed between them?

Accepted Answer

Like magnetic poles repel each other, so two north poles facing each other will experience a repulsive force.

Question 8

A rectangular coil of area 0.2 m² is placed perpendicular to a magnetic field of 2 T. Calculate the magnetic flux through the coil.

Accepted Answer

Using the formula Φ = BA cos θ, where B = 2 T, A = 0.2 m², and θ = 0° (perpendicular means cos 0° = 1), we get Φ = 2 × 0.2 × 1 = 0.4 Wb.

Question 9

Which of the following materials is best suited for making the core of an electromagnet?

Accepted Answer

Iron is a ferromagnetic material with high magnetic permeability, making it the best choice for electromagnet cores as it amplifies the magnetic field significantly.

Question 10

A wire of resistance 10 Ω is connected to a 5 V battery. What is the current flowing through the wire according to Ohm's Law?

Accepted Answer

Using Ohm's Law (V = IR), current I = V/R = 5/10 = 0.5 A.

Question 11

Two resistors of 6 Ω and 3 Ω are connected in parallel. What is their equivalent resistance?

Accepted Answer

For parallel resistors: 1/R_eq = 1/R₁ + 1/R₂ = 1/6 + 1/3 = 3/6 = 1/2, so R_eq = 2 Ω.

Question 12

A magnetic field of strength 0.5 T acts perpendicular to a straight conductor carrying a current of 4 A over a length of 2 m. Calculate the magnetic force on the conductor.

Accepted Answer

Using F = BIL (force on current-carrying conductor in magnetic field): F = 0.5 × 4 × 2 = 4 N.

Agniveer Army GD Electricity & Magnetism

Electricity & Magnetism — Practice Questions