When a current of 1 ampere is passed through a conductor whose ends are maintained at temperature difference of 1 ℃, the amount of heat evolved or absorbed is called
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(a) Peltier coefficient |
(b) Thomson coefficient |
|
(c) Thermoelectic power |
(d) Thermo e.m.f. |
(b) Thomson coefficient
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According to Mosley's law, the frequency of a spectral line in X-ray spectrum varies as
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(a) Atomic number of the element |
| (b) Square of the atomic number of the element |
| (c) Square root of the atomic number of the element |
|
(d) Fourth power of the atomic number of the element |
The transition from the state n = 4 to n = 3 in a hydrogen-like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition
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(a) 2 → 1 |
(b) 3 → 2 |
(c) 4 → 2 |
(d) 5 → 4 |
It is easier to start a car engine on a hot day than on a cold day. This is because the internal resistance of the car battery
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(a) Decreases with rise in temperature |
|
(b) Increases with rise in temperature |
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(c) Decreases with a fall in temperature |
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(d) Does not change with a change in temperature |
$\text{x}=\text{A}\sin(\text{ky}-\omega\text{t})$
$\text{y}=\text{A}\sin(\text{kx}-\omega\text{t})$
$\text{y}=\text{A}\sin\text{ky}\cos\ \omega\text{t}$
$\text{y}=\text{A}\cos\text{ky}\sin\ \omega\text{t}.$
For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
|
(a) ~ 1.2 |
(b) ~ |
(c) ~ |
(d) ~ |
An antenna is a device
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(a) That converts electromagnetic energy into radio frequency signal |
|
(b) That converts radio frequency signal into electromagnetic energy |
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(c) That converts guided electromagnetic waves into free space electromagnetic waves and vice-versa |
|
(d) None of these |
Assertion : The electrical conductivity of earth’s atmosphere decrease with altitude.
Reason : The high energy particles (i.e. g-rays and cosmic rays) coming from outer space and entering our earth’s atmosphere causes ionisation of the atoms of the gases present there and the pressure of gases decreases with increase in altitude.
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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. |
