When the current through a solenoid increases at a constant rate, the induced current
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(a) Is constant and is in the direction of the inducing current |
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(b) Is a constant and is opposite to the direction of the inducing current |
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(c) Increases with time and is in the direction of the inducing current |
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(d) Increases with time and opposite to the direction of the inducing current |
(b) Is a constant and is opposite to the direction of the inducing current
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Different voltages are applied across a P-N junction and the currents are measured for each value. Which of the following graphs is obtained between voltage and current
(a)
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(b)
|
(c)
|
(d)
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The resultant capacitance between A and B in the following figure is equal to
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(a) 1 μF |
(b) 3 μF |
(c) 2 μF |
(d) 1.5 μF |
Correct exposure for a photographic print is 10 seconds at a distance of one metre from a point source of 20 candela. For an equal fogging of the print placed at a distance of 2 m from a 16 candela source, the necessary time for exposure is
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(a) 100 sec |
(b) 25 sec |
(c) 50 sec |
(d) 75 sec |
The refractive index of water with respect to air is 4 / 3 and the refractive index of glass with respect to air is 3/2. The refractive index of water with respect to glass is
|
(a) |
(b) |
(c) |
(d) 2 |
The frequency of light ray having the wavelength 3000 Å is
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(a) 9 × 1013 cycles/sec |
(b) 1015 cycles/sec |
(c) 90 cycles/sec |
(d) 3000 cycles/sec |
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. |
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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. |
An air filled parallel plate capacitor has capacity C. If distance between plates is doubled and it is immersed in a liquid then capacity becomes twice. Dielectric constant of the liquid is
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(a) 1 |
(b) 2 |
(c) 3 |
(d) 4 |
The new resistance of wire of R W, whose radius is reduced half, is
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(a) 16 R |
(b) 3 R |
(c) 2R |
(d) R |
