- AAc only
- BDc only
- CEither ac or dc
- DNeither dc nor ac
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Blue colour of sky is due to:
While tuning in a certain broadcast station with a receiver, we are actually
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(a) Varying the local oscillator frequency |
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(b) Varying the frequency of the radio signal to be picked up |
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(c) Tuning the antenna |
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(d) None of these |
A 100 W bulb B1, and two 60-W bulbs B2 and B3, are connected to a 250 V source, as shown in the figure. Now W1, W2 and W3 are the output powers of the bulbs B1, B2 and B3, respectively. Then
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(a) |
(b) |
(c) |
(d) |
Assertion : Television signals are received through sky-wave propagation.
Reason : The ionosphere reflects electromagnetic waves of frequencies greater than a certain critical frequency.
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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. |
has half life 5700 years. At the end of 11400 years, the actual amount left is
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(a) 0.5 of original amount |
(b) 0.25 of original amount |
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(c) 0.125 of original amount |
(d) 0.0625 of original amount |