- ADue to the small packets called photons.
- BDue to an electric field.
- CLight does not travel as a wave.
- DDue to its electromagnetic nature.
Explanation:
Light travels as a wave due to its electromagnetic nature. This is further facilitated by Maxwell’s equations which states that changing magnetic fields give rise to electric fields and changing electric fields give rise to magnetic fields.
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A power transformer is used to step up an alternating e.m.f. of 220 V to 11 kV to transmit 4.4 kW of power. If the primary coil has 1000 turns, what is the current rating of the secondary ? Assume 100% efficiency for the transformer
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(a) 4 A |
(b) 0.4 A |
(c) 0.04 A |
(d) 0.2 A |
Antimony and bismuth are usually used in a thermocouple, because
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(a) Negative thermal e.m.f. produced |
(b) Constant thermal e.m.f. produced |
|
(c) Lower thermal e.m.f. produced |
(d) Higher thermal e.m.f. produced |
When a glass rod is rubbed with silk, it
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(a) Gains electrons from silk |
(b) Gives electrons to silk |
|
(c) Gains protons from silk |
(d) Gives protons to silk |
Assertion : A narrow pulse of light is sent through a medium. The pulse will retain its shape as it travels through the medium.
Reason : A narrow pulse is made of harmonic waves with a large range of wavelengths.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
Atomic power station at Tarapore has a generating capacity of 200 MW. The energy generated in a day by this station is
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(a) 200 MW |
(b) 200 J |
(c) 4800 |
(d) 1728 |