- AGold is easily available in nature.
- BGold is malleable.
- CGold is conducting in nature.
- DGold is cheap.
Explanation:
Though gold is a costly metal it is used in electroscope because of the property malleability. This means very thin and light sheets can be formed from gold simply by hammering or rolling and hence the deflection of the light gold plates increases.
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The current carrying wire and the rod AB are in the same plane. The rod moves parallel to the wire with a velocity v. Which one of the following statements is true about induced emf in the rod

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(a) End A will be at lower potential with respect to B |
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(b) A and B will be at the same potential |
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(c) There will be no induced e.m.f. in the rod |
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(d) Potential at A will be higher than that at B |
A coil having an area
is placed in a magnetic field which changes from
to
in a interval of 2 second. The e.m.f. induced in the coil will be
|
(a) 4 V |
(b) 3 V |
(c) 1.5 V |
(d) 2 V |
In a plano-convex lens the radius of curvature of the convex lens is 10 cm. If the plane side is polished, then the focal length will be (Refractive index = 1.5)
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(a) 10.5 cm |
(b) 10 cm |
(c) 5.5 cm |
(d) 5 cm |
The light of wavelength 6328 Å is incident on a slit of width 0.2 mm perpendicularly, the angular width of central maxima will be
|
(a) 0.36° |
(b) 0.18 ° |
(c) 0.72° |
(d) 0.09° |

Which of the following statement is not correct
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(a) Photographic plates are sensitive to infrared rays |
|
(b) Photographic plates are sensitive to ultraviolet rays |
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(c) Infra-red rays are invisible but can cast shadows like visible light |
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(d) Infrared photons have more energy than photons of visible light |