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प्रश्न
An electromagnetic radiation is used for photography in fog. [2]
(i) Identify the radiation.
(ii) Why is this radiation mentioned by you, ideal for this purpose ?
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उत्तर
(i) Infared radiation.
(ii) They have low frequency, the energy associated with them is also low so they do not scatter much and can penetrate appreciably through it.
संबंधित प्रश्न
Write one use of cathode ray tube.
Why is a cathode ray tube evacuated to a low pressure?
Radioactive substances were found to give off three types of rays. Name them. How do they
(a) React to the magnetic field?
(b) React to the electric field?
(c) Act when different thickness of lead sheets is placed in their path?
Why should a radioactive substance not be touched by hands?
What are ‘Becquerel rays’?
A certain nucleus has a mass number 20 and atomic number 9. Find the number of neutrons and protons present in it.
A radioactive element is placed in an evacuated chamber. Then the rate of radioactive decay will ______.
When an α-particle of mass m moving with velocity ν bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on m as:
Assertion (A): Hydrogen atom consists of only one electron but its emission spectrum has may lines.
Reason (R): Only Lyman series is found in the absorption spectrum of hydrogen atom whereas in the emission spectrum, all the series are found.
