NEET Magnetic Effects of Current and Magnetism — Set 5

Question 1

A solenoid with 2000 turns per meter carries $ 0.8 \, \text{A} $. What is the magnetic field inside? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

$ B = \mu_0 n I $. $ B = 4 \pi \times 10^{-7} \times 2000 \times 0.8 = 6.4 \pi \times 10^{-4} \approx 2.01 \times 10^{-3} \, \text{T} $.

Question 2

A circular coil of radius $ 0.1 \, \text{m} $ with 20 turns carries $ 4 \, \text{A} $. What is the magnetic field at the center? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

$ B = \frac{\mu_0 N I}{2 R} $. $ B = \frac{4 \pi \times 10^{-7} \times 20 \times 4}{2 \times 0.1} = \frac{32 \pi \times 10^{-6}}{0.2} = 16 \pi \times 10^{-5} \approx 5.03 \times 10^{-4} \, \text{T} $.

Question 3

A wire of length $ 0.5 \, \text{m} $ carrying $ 4 \, \text{A} $ is placed at $ 60^\circ $ to a magnetic field of $ 0.3 \, \text{T} $. What is the force on the wire?

Accepted Answer

Force $ F = I l B \sin \theta $. $ F = 4 \times 0.5 \times 0.3 \times \sin 60^\circ = 2 \times 0.3 \times 0.866 = 0.5196 \approx 0.52 \, \text{N} $.

NEET Physics: Magnetic Effects of Current and Magnetism — Practice Set 5

Q1. A solenoid with 2000 turns per meter carries \( 0.8 \, \text{A} \). What is the magnetic field inside? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q2. A circular coil of radius \( 0.1 \, \text{m} \) with 20 turns carries \( 4 \, \text{A} \). What is the magnetic field at the center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q3. A wire of length \( 0.5 \, \text{m} \) carrying \( 4 \, \text{A} \) is placed at \( 60^\circ \) to a magnetic field of \( 0.3 \, \text{T} \). What is the force on the wire?

Q4. A circular coil of 40 turns and radius \( 6 \, \text{cm} \) carries a current of \( 1 \, \text{A} \). What is the magnetic field at its center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q5. A rectangular loop of area \( 0.04 \, \text{m}^2 \) with 18 turns carries \( 2.8 \, \text{A} \) in a field of \( 0.9 \, \text{T} \) at \( 60^\circ \) to the plane. What is the torque?

Q6. What is the direction of the magnetic field at the center of a circular current-carrying loop?

Q7. Two parallel wires \( 0.08 \, \text{m} \) apart carry \( 7 \, \text{A} \) and \( 4 \, \text{A} \) in opposite directions. What is the force per unit length? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q8. A solenoid with 1500 turns per meter carries \( 1.1 \, \text{A} \). What is the magnetic field inside? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q9. A wire of length \( 1 \, \text{m} \) with \( 10 \, \text{A} \) is at \( 45^\circ \) to a field of \( 0.2 \, \text{T} \). What is the force on it?

Q10. What happens to the magnetic field inside a solenoid when the current through it is doubled?