NEET Magnetism and Matter — Set 12

Question 1

A solenoid with 1200 turns per meter and current $ 2.5 \, \text{A} $ has a core with $ \mu_r = 200 $. What is $ B $ inside? (Take $ \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} $).

Accepted Answer

$ B = \mu_0 \mu_r n I $. Given: $ n = 1200 \, \text{m}^{-1} $, $ I = 2.5 \, \text{A} $, $ \mu_r = 200 $, $ \mu_0 = 4\pi \times 10^{-7} $. $ B = 4\pi \times 10^{-7} \times 200 \times 1200 \times 2.5 = 0.7536 \, \text{T} \approx 0.75 \, \text{T} $.

Question 2

A bar magnet with original $ m = 1.6 \, \text{A m}^2 $ is cut transversely into two equal parts. What is $ m $ of each part?

Accepted Answer

When cut transversely, each part has half the original magnetic moment. Given: $ m = 1.6 \, \text{A m}^2 $. Each part: $ m' = \frac{1.6}{2} = 0.8 \, \text{A m}^2 $.

Question 3

A solenoid with 1200 turns per meter and current $ 2.5 \, \text{A} $ has a core with $ \mu_r = 150 $. What is $ B $ inside? (Take $ \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} $).

Accepted Answer

$ B = \mu_0 \mu_r n I $. Given: $ n = 1200 \, \text{m}^{-1} $, $ I = 2.5 \, \text{A} $, $ \mu_r = 150 $, $ \mu_0 = 4\pi \times 10^{-7} $. $ B = 4\pi \times 10^{-7} \times 150 \times 1200 \times 2.5 = 0.5652 \, \text{T} \approx 0.57 \, \text{T} $.

NEET Physics: Magnetism and Matter — Practice Set 12

Q1. A solenoid with 1200 turns per meter and current \( 2.5 \, \text{A} \) has a core with \( \mu_r = 200 \). What is \( B \) inside? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q2. A bar magnet with original \( m = 1.6 \, \text{A m}^2 \) is cut transversely into two equal parts. What is \( m \) of each part?

Q3. A solenoid with 1200 turns per meter and current \( 2.5 \, \text{A} \) has a core with \( \mu_r = 150 \). What is \( B \) inside? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q4. A material with susceptibility \( \chi = 2 \times 10^{-3} \) has a relative permeability \( \mu_r \) of:

Q5. A solenoid with 400 turns per meter carries a current of \( 5 \, \text{A} \). What is the magnetic intensity \( H \) inside?

Q6. A solenoid produces \( B = 1.2 \, \text{T} \) with a core of \( \mu_r = 400 \) and \( n = 1500 \, \text{m}^{-1} \). What is the current \( I \)? (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q7. The magnetic potential energy of a dipole with \( m = 0.6 \, \text{A m}^2 \) in a field \( B = 0.2 \, \text{T} \) at \( 0^\circ \) is:

Q8. A material with \( B = 0.36 \, \text{T} \) and \( H = 2500 \, \text{A m}^{-1} \) has \( M \): (Take \( \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} \)).

Q9. Which material has a large positive \( \chi \) and exhibits spontaneous domain alignment?

Q10. Which material has \( \chi \) slightly positive and moves from weaker to stronger field regions?