A bar magnet of length l and magnetic dipole moment M is bent to form an arc which subtends an angle of at centre. The new magnetic dipole moment will be
1.
2.
3.
4.
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A small bar magnet is placed with its north pole facing magnetic north pole. The neutral points are located at distance r from its centre. If magnet is rotated by 180o, neutral point shall be obtained at distance
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Difficulty Level:
Two small bar magnets are placed in air at a distance r apart. The magnetic force between them is proportional to
(1)
(2)
(3)
(4)
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A short magnetic dipole is placed at the origin with its dipole movement directed along the +x-axis. If magnetic field induction at a point P (r, 0) is B, the magnetic field induction at point Q(0,2r) will be
(1)
(2)
(3)
(4)
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Difficulty Level:
The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the centre of the magnet is
(a)
(b)
(c)
(d)
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A magnet of magnetic moment 20 C.G.S. units are freely suspended in a uniform magnetic field of intensity 0.3 C.G.S. units. The amount of work done in deflecting it by an angle of in C.G.S. units is
(a) 6
(b)
(c)
(d) 3
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The magnetic field due to a short magnet at a point on its axis at a distance X cm from the middle point of the magnet is 200 Gauss. The magnetic field at a point on the neutral axis at a distance of X cm from the middle of the magnet is
1. 100 Gauss
2. 400 Gauss
3. 50 Gauss
4. 200 Gauss
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A sensitive magnetic instrument can be shielded very effectively from outside magnetic fields by placing it inside a box of
1. Teak wood
2. Plastic material
3. Soft iron of high permeability
4. A metal of high conductivity
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