NEET Magnetic Effects of Current and Magnetism — Set 3

Question 1

A circular coil of radius $ 0.15 \, \text{m} $ with 20 turns carries $ 2.8 \, \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 2.8}{2 \times 0.15} = \frac{22.4 \pi \times 10^{-6}}{0.3} = 7.4667 \pi \times 10^{-5} \approx 2.35 \times 10^{-4} \, \text{T} $.

Question 2

A solenoid with 1750 turns per meter carries a current of $ 1.8 \, \text{A} $. What is the magnetic field inside it? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

Magnetic field $ B = \mu_0 n I $. $ B = 4 \pi \times 10^{-7} \times 1750 \times 1.8 = 12.6 \pi \times 10^{-4} \approx 3.96 \times 10^{-3} \, \text{T} $.

Question 3

Two parallel wires $ 0.05 \, \text{m} $ apart carry currents of $ 8 \, \text{A} $ and $ 3 \, \text{A} $ in the same direction. What is the force per unit length between them? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

Force per unit length $ f = \frac{\mu_0 I_1 I_2}{2 \pi d} $. $ f = \frac{4 \pi \times 10^{-7} \times 8 \times 3}{2 \pi \times 0.05} = \frac{96 \times 10^{-7}}{0.1} = 9.6 \times 10^{-6} \, \text{N/m} $.

NEET Physics: Magnetic Effects of Current and Magnetism — Practice Set 3

Q1. A circular coil of radius \( 0.15 \, \text{m} \) with 20 turns carries \( 2.8 \, \text{A} \). What is the magnetic field at the center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q2. A solenoid with 1750 turns per meter carries a current of \( 1.8 \, \text{A} \). What is the magnetic field inside it? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q3. Two parallel wires \( 0.05 \, \text{m} \) apart carry currents of \( 8 \, \text{A} \) and \( 3 \, \text{A} \) in the same direction. What is the force per unit length between them? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q4. An electron moves at \( 6 \times 10^6 \, \text{m/s} \) perpendicular to a field of \( 0.4 \, \text{T} \). What is the magnetic force? (Charge = \( 1.6 \times 10^{-19} \, \text{C} \))

Q5. A wire of length \( 1.3 \, \text{m} \) carrying \( 6 \, \text{A} \) is at \( 45^\circ \) to a magnetic field of \( 0.8 \, \text{T} \). What is the force on the wire?

Q6. Two parallel wires \( 0.04 \, \text{m} \) apart carry \( 10 \, \text{A} \) and \( 4 \, \text{A} \) in opposite directions. What is the force per unit length? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q7. A rectangular loop of area \( 0.08 \, \text{m}^2 \) with 10 turns carries \( 4 \, \text{A} \) in a field of \( 0.9 \, \text{T} \) perpendicular to the plane. What is the torque?

Q8. A circular coil of 60 turns and radius \( 8 \, \text{cm} \) carries a current of \( 0.9 \, \text{A} \). What is the magnetic field at its center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q9. What is the primary source of the magnetic field in a solenoid?

Q10. A square loop of side \( 0.1 \, \text{m} \) with 25 turns carries \( 2 \, \text{A} \) in a magnetic field of \( 0.8 \, \text{T} \). The plane of the loop makes \( 30^\circ \) with the field. What is the torque?