While using an electric bulb, the reflection for street lighting should be from
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(a) Concave mirror |
(b) Convex mirror |
(d) Parabolic mirror |
(d) Parabolic mirror |
(b) Convex mirror
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Assertion : Penetrating power of X-rays increases with the increasing the wavelength.
Reason : The penetrating power of X-rays increases with the frequency of X-rays.
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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. |
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(c) If assertion is true but reason is false. |
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(d) If assertion is false but reason is true. |
The radio waves of frequency 300 MHz to 3000 MHz belong to
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(a) High frequency band |
(b) Very high frequency band |
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(c) Ultra high frequency band |
(d) Super high frequency band |
Some radioactive nucleus may emit
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(a) Only one α,β or γ at a time |
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(b) All the three α,β and γ one after another |
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(c) All the three α,β and γ simultaneously |
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(d) Only α and β simultaneously |
In a radioactive substance at t = 0, the number of atoms is 8 
. Its half life period is 3 years. The number of atoms 1 will remain after interva
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(a) 9 yearss |
(b) 8 years |
(c) 6 years |
(d) 24 years |
The angular dispersion produced by a prism:
$\text{y}=(0.001\text{mm})\sin\Big[(50\text{s}^{-1})\text{t}+(2.0\text{m}^{-1})\text{x}\Big]$
Which of the following radiations has the least wavelength
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(a) g -rays |
(b) b-rays |
(c) a-rays |
(d) X-rays |