- AForm closed circuits.
- BCannot intersect.
- CAre crowded together near the poles.
- DAll the above are correct.
Explanation:
They always form complete closed loops. Unlike lines of electric flux which radiate from and terminate at the charged surfaces, lines of magnetic flux exist all the way through the magnet.
They behave as if they are elastic. That is, when distorted they try to return to their natural shape and spacing.
The lines of force of magnetic field are radiated from the north (N) pole to the south (S) pole.
Flux lines do not cross or interact to each other.
The density of lines of magnetic force indicates the strength of field at the point. Since strength is greatest at the poles, the magnetic lines of force are crowded there.
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An object of size 7.5 cm is placed in front of a convex mirror of radius of curvature 25 cm at a distance of 40 cm The size of the image should be
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(a) 2.3 cm |
(b) 1.78 cm |
(c) 1 cm |
(d) 0.8 cm |
If
and
are respectively, the electric permittivity and the magnetic permeability of free space, ε and μ the corresponding quantities in a medium, the refractive index of the medium is
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(a) |
(b) |
(c) |
(d) |
The electric field inside a spherical shell of uniform surface charge density is
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(a) Zero |
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(b) Constant, less than zero |
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(c) Directly proportional to the distance from the centre |
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(d) None of the above |
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(a) |
(b) |
(c) |
(d) |
The variation of magnetic susceptibility (x) with temperature for a diamagnetic substance is best represented by
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(a) |
(b) |
(c) |
(d) |
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(a) 4πiM |
(b) |
(c) |
(d) |
Which of the following rays has the maximum frequency
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(a) Gamma rays |
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(c) Infrared rays |
(d) Ultraviolet rays |
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(a) 4 A |
(b) 0.4 A |
(c) 0.04 A |
(d) 0.2 A |
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(a) Allow us to find the focal length of a thick lens |
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(b) Is a geometrical method to find a wavefront |
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(c) Is used to determine the velocity of light |
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(d) Is used to explain polarisation |