NEET Magnetic Effects of Current and Magnetism — Set 14

Question 1

Two parallel wires $ 0.12 \, \text{m} $ apart carry currents of $ 4 \, \text{A} $ and $ 7 \, \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 4 \times 7}{2 \pi \times 0.12} = \frac{112 \times 10^{-7}}{0.24} = 4.67 \times 10^{-6} \, \text{N/m} $.

Question 2

A rectangular loop of area $ 0.06 \, \text{m}^2 $ with 15 turns carries $ 2.5 \, \text{A} $ in a field of $ 0.8 \, \text{T} $ at $ 60^\circ $ to the plane. What is the torque?

Accepted Answer

$ \tau = N I A B \sin \theta $, where $ \theta = 60^\circ $ to plane means $ \sin 30^\circ $ with normal. $ \tau = 15 \times 2.5 \times 0.06 \times 0.8 \times \sin 60^\circ = 1.8 \times 0.866 = 1.5588 \approx 1.56 \, \text{N m} $.

Question 3

A solenoid has 600 turns per meter and carries a current of $ 3 \, \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 600 \times 3 = 7.2 \pi \times 10^{-4} \approx 2.26 \times 10^{-3} \, \text{T} $.

NEET Physics: Magnetic Effects of Current and Magnetism — Practice Set 14

Q1. Two parallel wires \( 0.12 \, \text{m} \) apart carry currents of \( 4 \, \text{A} \) and \( 7 \, \text{A} \) in the same direction. What is the force per unit length between them? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q2. A rectangular loop of area \( 0.06 \, \text{m}^2 \) with 15 turns carries \( 2.5 \, \text{A} \) in a field of \( 0.8 \, \text{T} \) at \( 60^\circ \) to the plane. What is the torque?

Q3. A solenoid has 600 turns per meter and carries a current of \( 3 \, \text{A} \). What is the magnetic field inside it? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q4. A solenoid with 1100 turns per meter carries \( 1.8 \, \text{A} \). What is the magnetic field inside? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q5. A solenoid has 1250 turns per meter and carries a current of \( 1.5 \, \text{A} \). What is the magnetic field inside it? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q6. An electron moves at \( 2.5 \times 10^6 \, \text{m/s} \) perpendicular to a field of \( 0.5 \, \text{T} \). What is the radius of its path? (Mass = \( 9.1 \times 10^{-31} \, \text{kg} \), charge = \( 1.6 \times 10^{-19} \, \text{C} \))

Q7. An electron moves at \( 6.5 \times 10^6 \, \text{m/s} \) perpendicular to a field of \( 0.2 \, \text{T} \). What is the radius of its path? (Mass = \( 9.1 \times 10^{-31} \, \text{kg} \), charge = \( 1.6 \times 10^{-19} \, \text{C} \))

Q8. What is the shape of the magnetic field lines produced by a straight current-carrying wire?

Q9. A long straight wire carries a current of \( 40 \, \text{A} \). What is the magnetic field at a distance of \( 0.5 \, \text{m} \) from it? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q10. A long straight wire carries a current of \( 10 \, \text{A} \). What is the magnetic field at a point \( 0.1 \, \text{m} \) from the wire? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))