NEET Magnetic Effects of Current and Magnetism — Set 15

Question 1

A circular coil of 45 turns and radius $ 6 \, \text{cm} $ carries a current of $ 1.2 \, \text{A} $. What is the magnetic field at its center? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

Magnetic field $ B = \frac{\mu_0 N I}{2 R} $. $ B = \frac{4 \pi \times 10^{-7} \times 45 \times 1.2}{2 \times 0.06} = \frac{21.6 \pi \times 10^{-6}}{0.12} = 1.8 \pi \times 10^{-4} \approx 5.65 \times 10^{-4} \, \text{T} $.

Question 2

A circular loop of radius $ 0.08 \, \text{m} $ with 60 turns carries a current of $ 0.75 \, \text{A} $. What is the magnetic field at the center? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

Magnetic field $ B = \frac{\mu_0 N I}{2 R} $. $ B = \frac{4 \pi \times 10^{-7} \times 60 \times 0.75}{2 \times 0.08} = \frac{18 \pi \times 10^{-6}}{0.16} = 1.125 \pi \times 10^{-4} \approx 3.53 \times 10^{-4} \, \text{T} $.

Question 3

A long wire carries $ 15 \, \text{A} $. At what distance is the magnetic field $ 3 \times 10^{-6} \, \text{T} $? ($ \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} $)

Accepted Answer

$ B = \frac{\mu_0 I}{2 \pi r} $, so $ r = \frac{\mu_0 I}{2 \pi B} $. $ r = \frac{4 \pi \times 10^{-7} \times 15}{2 \pi \times 3 \times 10^{-6}} = \frac{60 \times 10^{-7}}{6 \times 10^{-6}} = 1 \, \text{m} $.

NEET Physics: Magnetic Effects of Current and Magnetism — Practice Set 15

Q1. A circular coil of 45 turns and radius \( 6 \, \text{cm} \) carries a current of \( 1.2 \, \text{A} \). What is the magnetic field at its center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q2. A circular loop of radius \( 0.08 \, \text{m} \) with 60 turns carries a current of \( 0.75 \, \text{A} \). What is the magnetic field at the center? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q3. A long wire carries \( 15 \, \text{A} \). At what distance is the magnetic field \( 3 \times 10^{-6} \, \text{T} \)? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q4. A solenoid with 1400 turns per meter carries a current of \( 2.5 \, \text{A} \). What is the magnetic field inside it? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q5. A square loop of side \( 0.15 \, \text{m} \) with 50 turns carries \( 1 \, \text{A} \) in a magnetic field of \( 0.6 \, \text{T} \). The plane of the loop is at \( 30^\circ \) to the field. What is the torque?

Q6. A wire of length \( 0.8 \, \text{m} \) carrying \( 5 \, \text{A} \) is at \( 30^\circ \) to a magnetic field of \( 0.8 \, \text{T} \). What is the force on the wire?

Q7. Two parallel wires \( 0.08 \, \text{m} \) apart carry currents of \( 5 \, \text{A} \) and \( 3 \, \text{A} \) in the same direction. What is the force per unit length between them? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q8. An electron moves at \( 7 \times 10^6 \, \text{m/s} \) perpendicular to a field of \( 0.2 \, \text{T} \). What is the magnetic force? (Charge = \( 1.6 \times 10^{-19} \, \text{C} \))

Q9. A long wire carries \( 14 \, \text{A} \). At what distance is the magnetic field \( 7 \times 10^{-6} \, \text{T} \)? (\( \mu_0 = 4 \pi \times 10^{-7} \, \text{T m/A} \))

Q10. Which property of magnetic field lines distinguishes them from electric field lines?