NEET Magnetism and Matter — Set 3

Question 1

The magnetic flux through a closed surface is always zero. This statement is a consequence of:

Accepted Answer

The absence of magnetic monopoles means that magnetic field lines are continuous and form closed loops. As a result, the number of field lines entering a closed surface equals the number leaving it, leading to a net magnetic flux of zero, as per Gauss’s law for magnetism.

Question 2

A material with susceptibility $ \chi = -6 \times 10^{-5} $ has a relative permeability $ \mu_r $ of:

Accepted Answer

$ \mu_r = 1 + \chi $. Given: $ \chi = -6 \times 10^{-5} $. Substitute: $ \mu_r = 1 - 6 \times 10^{-5} = 0.99994 $.

Question 3

A ferromagnetic material has $ \mu_r = 1000 $ and $ H = 500 \, \text{A m}^{-1} $. What is the magnetic field $ B $ inside? (Take $ \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} $).

Accepted Answer

$ B = \mu_0 \mu_r H $. Given: $ \mu_r = 1000 $, $ H = 500 \, \text{A m}^{-1} $, $ \mu_0 = 4\pi \times 10^{-7} $. Substitute: $ B = 4\pi \times 10^{-7} \times 1000 \times 500 = 0.628 \, \text{T} \approx 0.63 \, \text{T} $.

NEET Physics: Magnetism and Matter — Practice Set 3

Q1. The magnetic flux through a closed surface is always zero. This statement is a consequence of:

Q2. A material with susceptibility \( \chi = -6 \times 10^{-5} \) has a relative permeability \( \mu_r \) of:

Q3. A ferromagnetic material has \( \mu_r = 1000 \) and \( H = 500 \, \text{A m}^{-1} \). What is the magnetic field \( B \) inside? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q4. The magnetic potential energy of a dipole with \( m = 0.9 \, \text{A m}^2 \) in a field \( B = 0.4 \, \text{T} \) at \( 90^\circ \) is:

Q5. A solenoid produces \( B = 0.6 \, \text{T} \) with a core of \( \mu_r = 200 \) and \( n = 1000 \, \text{m}^{-1} \). What is the current \( I \)? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q6. The reason a superconductor can levitate a magnet is:

Q7. A solenoid with 400 turns per meter carries a current of \( 6 \, \text{A} \). What is the magnetic intensity \( H \) inside?

Q8. The reason a magnetic field does not exert a force along its own direction on a moving charge is:

Q9. A material with \( \mu_r = 600 \) and \( H = 400 \, \text{A m}^{-1} \) has \( B \): (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q10. A solenoid with 700 turns per meter carries a current of \( 3 \, \text{A} \). What is the magnetic intensity \( H \) inside?