A triangular loop of side l carries a current I. It is placed in a magnetic field B such that the plane of the loop is in the direction of B. The torque on the loop is
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(a) Zero |
(b) IBl |
(c) |
(d) |
(d) 
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An infinitely long, straight conductor AB is fixed and a current is passed through it. Another movable straight wire CD of finite length and carrying current is held perpendicular to it and released. Neglect weight of the wire
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(a) The rod CD will move upwards parallel to itself |
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(b) The rod CD will move downward parallel to itself |
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(c) The rod CD will move upward and turn clockwise at the same time |
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(d) The rod CD will move upward and turn anti –clockwise at the same time |
A capacitor is kept connected to the battery and a dielectric slab is inserted between the plates. During this process
|
(a) No work is done |
|
(b) Work is done at the cost of the energy already stored in the capacitor before the slab is inserted |
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(c) Work is done at the cost of the battery |
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(d) Work is done at the cost of both the capacitor and the battery |
Two batteries, one of emf 18 volts and internal resistance 2Ω and the other of emf 12 volt and internal resistance 1 Ω, are connected as shown. The voltmeter V will record a reading of
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(a) 15 volt |
(b) 30 volt |
(c) 14 volt |
(d) 18 volt |
A steady current i flows in a small square loop of wire of side L in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let 
and 
respectively denote the magnetic moments due to the current loop before and after folding. Then
|
(a) |
(b) |
|
(c) |
(d) |
