Doppler's effect in sound in addition to relative velocity between source and observer, also depends while source and observer or both are moving. Doppler effect in light depend only on the relative velocity of source and observer. The reason of this is
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(a) Einstein mass - energy relation |
(b) Einstein theory of relativity |
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(c) Photoelectric effect |
(d) None of these |
(b) Einstein theory of relativity
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A step up transformer has transformation ration 5 : 3. What is voltage in secondary if voltage in primary is 60 V
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(a) 20 V |
(b) 60 V |
(c) 100 V |
(d) 180 V |
A concave mirror of focal length 15 cm forms an image having twice the linear dimensions of the object. The position of the object when the image is virtual will be
|
(a) 22.5 cm |
(b) 7.5 cm |
(c) 30 cm |
(d) 45 cm |
The electric field due to an electric dipole at a distance r from its centre in axial position is E. If the dipole is rotated through an angle of 90° about its perpendicular axis, the electric field at the same point will be
|
(a) E |
(b) E/4 |
(c) E/2 |
(d) 2E |
Of the diodes shown in the following diagrams, which one is reverse biased
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(a)
|
(b)
|
(c)
|
(d)
|
A glass rod rubbed with silk is used to charge a gold leaf electroscope and the leaves are observed to diverge. The electroscope thus charged is exposed to X-rays for a short period. Then
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(a) The divergence of leaves will not be affected |
|
(b) The leaves will diverge further |
|
(c) The leaves will collapse |
|
(d) The leaves will melt |
For reading small letters with a lens:
Dispersion can take place for
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(a) Transverse waves only but not for longitudinal waves |
|
(b) Longitudinal waves only but not for transverse waves |
|
(c) Both transverse and longitudinal waves |
|
(d) Neither transverse nor longitudinal waves |
The resistance of an ideal ammeter is
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(a) Infinite |
(b) Very high |
(c) Small |
(d) Zero |
