- AA moving charge.
- BA changing electric field.
- CNone of these.
- DBoth of these.
Explanation:
A moving charge and changing electric field both produces magnetic field.
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Assertion : Moon is seen as it partly reflects the sun light falling on it
Reason : Moon is a satellite of earth. It does not emit light of its own
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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 the assertion and reason both are false. |
The mass equivalent of 931 MeV energy is
|
(a) 1.66 |
(b) 6.02 |
(c) 1.66 |
(d) 6.02 |
The thermo e.m.f. of a thermo-couple is 25μV/℃ at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as , is connected with the thermocouple. The smallest temperature difference that can be detected by this system is
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(a) 20 ℃ |
(b) 16 ℃ |
(c) 12 ℃ |
(d) 8℃ |
For the production of X-rays, the target should be made of
|
(a) Steel |
(b) Copper |
(c) Aluminum |
(d) Tungsten |
The resistance of a 5 cm long wire is 10 W. It is uniformly stretched so that its length becomes 20 cm. The resistance of the wire is
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(a) 160 W |
(b) 80 W |
(c) 40 W |
(d) 20 W |
The half-life of radioactive Polonium (Po) is 138.6 days. For ten lakh Polonium atoms, the number of disintegrations in 24 hours is
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(a) 2000 |
(b) 3000 |
(c) 4000 |
(d) 5000 |
The insulated spheres of radii
and
having charges
and
respectively are connected to each other. There is
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(a) No change in the energy of the system |
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(b) An increase in the energy of the system |
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(c) Always a decrease in the energy of the system |
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(d) A decrease in the energy of the system unless |
What type of modulation is employed in India for radio transmission
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(a) Amplitude modulation |
(b) Frequency modulation |
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(c) Pulse modulation |
(d) None of these |
In optical instruments, the lenses are used to form images by: