The outer sphere of a spherical air capacitor is earthed. For increasing its capacitance
|
(a) Vacuum is created between two spheres |
|
(b) Dielectric material is filled between the two spheres |
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(c) The space between two spheres is increased |
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(d) The earthing of the outer sphere is removed |
(b) Dielectric material is filled between the two spheres
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The magnet can be completely demagnetized by
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(a) Breaking the magnet into small pieces |
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(b) Heating it slightly |
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(c) Droping it into ice cold water |
|
(d) A reverse field of appropriate strength |
If the refractive indices of a prism for red, yellow and violet colours be 1.61, 1.63 and 1.65 respectively, then the dispersive power of the prism will be
|
(a) |
(b) |
(c) |
(d) |
Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity
|
(a) Decreases |
(b) Increases |
(c) Remains unchanged |
(d) Becomes zero |
The critical angle of a medium with respect to air is 45°. The refractive index of medium is
|
(a) 1.41 |
(b) 1.2 |
(c) 1.5 |
(d) 2 |
Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance 5 m between them. If P and Q carry current of 2.5 amp and 5 amp respectively in the same direction, then the magnetic field at a point half way between the wires is
|
(a) |
(b) |
(c) |
(d) |
Young's experiment is performed in air and then performed in water, the fringe width
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(a) Will remain same |
(b) Will decrease |
(c) Will increase |
(d) Will be infinite |
