Moving Charges and Magnetism - Result Question 66

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67. A closely wound solenoid of 2000 turns and area of cross-section $1.5 \times 10^{-4} m^{2}$ carries a current of $2.0 A$. It suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field $5 \times 10^{-2}$ tesla making an angle of $30^{\circ}$ with the axis of the solenoid. The torque on the solenoid will be:

======= ####67. A closely wound solenoid of 2000 turns and area of cross-section $1.5 \times 10^{-4} m^{2}$ carries a current of $2.0 A$. It suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field $5 \times 10^{-2}$ tesla making an angle of $30^{\circ}$ with the axis of the solenoid. The torque on the solenoid will be:

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/moving-charges-and-magnetism/moving-charges-and-magnetism—result-question-66.md (a) $3 \times 10^{-2} N-m$

(b) $3 \times 10^{-3} N-m$

(c) $1.5 \times 10^{-3} N-m$

(d) $1.5 \times 10^{-2} N-m$

[2010]

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Answer:

Correct Answer: 67. (d)

Solution:

  1. (d) Torque on the solenoid is given by $\tau=M B \sin \theta$

where $\theta$ is the angle between the magnetic field and the axis of solenoid.

$M=$ niA

$\therefore \tau=n i A B \sin 30^{\circ}$

$=2000 \times 2 \times 1.5 \times 10^{-4} \times 5 \times 10^{-2} \times \frac{1}{2}$

$=1.5 \times 10^{-2} N-m$