- A$\Omega\text{m}^{-1}$
- B$\Omega^{-1}\text{m}^{-1}$
- C$\Omega1$
- D$2.5-\text{m}^2$
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An image of the sun is formed by a lens of focal length of 30 cm on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is
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(a) |
(b) I |
(c) 2I |
(d) 4I |
In an experiment, the saturation in the plate current in a diode is observed at 240V. But a student still wants to increase the plate current. It can be done, if
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(a) The plate voltage is increased further |
|
(b) The plate voltage is decreased |
|
(c) The filament current is decreased |
|
(d) The filament current is increased |
In a spherical condenser radius of the outer sphere is R. The different in the radii of outer and inner sphere in x. Its capacity is proportional to
|
(a) |
(b) |
(c) |
(d) |
A spectrum is formed by a prism of dispersive power ‘ω’. If the angle of deviation is ‘δ’, then the angular dispersion is
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(a) ω/δ |
(b) δ / ω |
(c) 1/ ωδ |
(d) ω δ |
A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5º and the prism is made of a material of refractive index 1.5, the angle of incidence is:
When the number of turns in a coil is doubled without any change in the length of the coil, its self inductance becomes
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(a) Four times |
(b) Doubled |
(c) Halved |
(d) Unchanged |