NEET Magnetism and Matter — Set 9

Question 1

The magnetic field contribution $ B_m $ due to a material with $ M = 3.5 \times 10^5 \, \text{A m}^{-1} $ is: (Take $ \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} $).

Accepted Answer

$ B_m = \mu_0 M $. Given: $ M = 3.5 \times 10^5 \, \text{A m}^{-1} $, $ \mu_0 = 4\pi \times 10^{-7} $. $ B_m = 4\pi \times 10^{-7} \times 3.5 \times 10^5 = 0.4396 \, \text{T} \approx 0.44 \, \text{T} $.

Question 2

A dipole with $ m = 0.25 \, \text{A m}^2 $ in a field $ B = 0.4 \, \text{T} $ at $ 90^\circ $ has potential energy:

Accepted Answer

$ U_m = -m B \cos\theta $. Given: $ m = 0.25 \, \text{A m}^2 $, $ B = 0.4 \, \text{T} $, $ \theta = 90^\circ $, $ \cos 90^\circ = 0 $. $ U_m = -0.25 \times 0.4 \times 0 = 0 \, \text{J} $.

Question 3

Which material has a large positive $ \chi $ and forms domains?

Accepted Answer

Ferromagnetic materials have large positive $ \chi $ and exhibit domain formation due to spontaneous alignment of magnetic moments.

NEET Physics: Magnetism and Matter — Practice Set 9

Q1. The magnetic field contribution \( B_m \) due to a material with \( M = 3.5 \times 10^5 \, \text{A m}^{-1} \) is: (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q2. A dipole with \( m = 0.25 \, \text{A m}^2 \) in a field \( B = 0.4 \, \text{T} \) at \( 90^\circ \) has potential energy:

Q3. Which material has a large positive \( \chi \) and forms domains?

Q4. A material’s susceptibility becomes large and positive when its microscopic regions align spontaneously. This is a feature of:

Q5. A magnetic dipole in a uniform field is in unstable equilibrium when:

Q6. A material has a magnetic susceptibility \( \chi = 0.001 \). What is its relative magnetic permeability \( \mu_r \)?

Q7. A solenoid produces \( B = 0.96 \, \text{T} \) with a core of \( \mu_r = 300 \) and \( n = 1000 \, \text{m}^{-1} \). What is the current \( I \)? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q8. A dipole with \( m = 0.7 \, \text{A m}^2 \) in \( B = 0.2 \, \text{T} \) at \( 45^\circ \) has torque:

Q9. A material with susceptibility \( \chi = -4 \times 10^{-5} \) has a relative permeability \( \mu_r \) of:

Q10. A magnetic dipole oscillates in a uniform field when displaced from its equilibrium position because: