- A$\Big(\frac{\text{R}_1}{\text{R}_2}\Big)^{\frac{1}{2}}$
- B$\Big(\frac{\text{R}_2}{\text{R}_1}\Big)$
- C$\Big(\frac{\text{R}_1}{\text{R}_2}\Big)^2$
- D$\Big(\frac{\text{R}_1}{\text{R}_2}\Big)$
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The magnetic field lines due to a bar magnet are correctly shown in
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(a)
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(b)
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(c)
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(d)
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A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of
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(a) Each of these increases |
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(b) Each of these decreases |
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(c) Copper strip increases and that of germanium decreases |
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(d) Copper strip decreases and that of germanium increases |
A plano-convex lens of refractive index 1.5 and radius of curvature 30 cm is silvered at the curved surface. Now this lens has been used to form the image of an object. At what distance from this lens an object be placed in order to have a real image of the size of the object
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(a) 20 cm |
(b) 30 cm |
(c) 60 cm |
(d) 80 cm |
A metallic loop is placed in a magnetic field. If a current is passed through it, then
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(a) The ring will feel a force of attraction |
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(b) The ring will feel a force of repulsion |
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(c) It will move to and fro about its centre of gravity |
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(d) None of these |
Which of the following, the most suitable material for making permanent magnet is
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(a) Steel |
(b) Soft iron |
(c) Copper |
(d) Nickel |
In Young’s double slit experiment, the two slits act as coherent sources of equal amplitude A and wavelength l. In another experiment with the same set up the two slits are of equal amplitude A and wavelength l but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is
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(a) 1 : 2 |
(b) 2 : 1 |
(c) 4 : 1 |
(d) 1 : 1 |
A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V. If the shell is now given a charge of –3Q, the new potential difference between the same two surfaces is
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(a) V |
(b) 2V |
(c) 4V |
(d) – 2V |
The field normal to the plane of a wire of n turns and radius r which carries a current i is measured on the axis of the coil at a small distance h from the centre of the coil. This is smaller than the field at the centre by the fraction
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(a) |
(b) |
(c) |
(d) |