NEET Magnetism and Matter — Set 17

Question 1

The net magnetic flux through a closed surface surrounding a solenoid is:

Accepted Answer

Gauss’s law for magnetism states that the net magnetic flux through any closed surface is zero, as magnetic field lines form closed loops with no monopoles.

Question 2

A dipole with $ m = 0.7 \, \text{A m}^2 $ in a field $ B = 0.4 \, \text{T} $ at $ 180^\circ $ has potential energy:

Accepted Answer

$ U_m = -m B \cos\theta $. Given: $ m = 0.7 \, \text{A m}^2 $, $ B = 0.4 \, \text{T} $, $ \theta = 180^\circ $, $ \cos 180^\circ = -1 $. $ U_m = -0.7 \times 0.4 \times (-1) = 0.28 \, \text{J} $.

Question 3

A paramagnetic material has $ \chi = 5 \times 10^{-4} $ and $ H = 2 \times 10^3 \, \text{A m}^{-1} $. What is its magnetization $ M $?

Accepted Answer

$ M = \chi H $. Given: $ \chi = 5 \times 10^{-4} $, $ H = 2 \times 10^3 \, \text{A m}^{-1} $. Substitute: $ M = 5 \times 10^{-4} \times 2 \times 10^3 = 1 \, \text{A m}^{-1} $.

NEET Physics: Magnetism and Matter — Practice Set 17

Q1. The net magnetic flux through a closed surface surrounding a solenoid is:

Q2. A dipole with \( m = 0.7 \, \text{A m}^2 \) in a field \( B = 0.4 \, \text{T} \) at \( 180^\circ \) has potential energy:

Q3. A paramagnetic material has \( \chi = 5 \times 10^{-4} \) and \( H = 2 \times 10^3 \, \text{A m}^{-1} \). What is its magnetization \( M \)?

Q4. A solenoid with 900 turns per meter and current \( 3 \, \text{A} \) has a core with \( \mu_r = 250 \). What is \( B \) inside? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q5. A bar magnet’s field strength decreases with distance because:

Q6. A solenoid has 500 turns per meter and carries a current of \( 3 \, \text{A} \). What is the magnetic intensity \( H \) inside the solenoid?

Q7. The net magnetic flux through a closed surface surrounding a bar magnet is:

Q8. A bar magnet with \( m = 2.5 \, \text{A m}^2 \) is at \( 0.7 \, \text{m} \) along its axis. What is \( B \)? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q9. The magnetic potential energy of a dipole with \( m = 0.7 \, \text{A m}^2 \) in a field \( B = 0.2 \, \text{T} \) at \( 0^\circ \) is:

Q10. A magnetic dipole of moment \( 0.5 \, \text{A m}^2 \) is in a uniform field of \( 0.3 \, \text{T} \) at \( 60^\circ \). What is the torque on it?