The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to
(a) 
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(b) 
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(c) 1/
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(d) 1/V |
(d) 1/V
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The plates of a parallel plate capacitor of capacity 50 μC are charged to a potential of 100 volts and then separated from each other so that the distance between them is doubled. How much is the energy spent in doing so
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(a) 25 |
(b) -12.5 |
(c) -25 |
(d) 12.5 |
A rectangular loop with a sliding connector of length l = 1.0 m is situated in a uniform magnetic field B = 2T perpendicular to the plane of loop. Resistance of connector is r = 2W. Two resistance of 6W and 3W are connected as shown in figure. The external force required to keep the connector moving with a constant velocity v = 2m/s is
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(a) 6 N |
(b) 4 N |
(c) 2 N |
(d) 1 N |
Assertion : A current I flows along the length of an infinitely long straight and thin walled pipe. Then the magnetic field at any point inside the pipe is zero.
Reason : 
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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 photoelectric threshold wavelength for potassium (work function being 2eV ) is
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(a) 310 nm |
(b) 620 nm |
(c) 1200 nm |
(d) 2100 nm |
In the figure shown, the effective capacitance between the points A and B, if each has capacitance C, is
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(a) 2C |
(b) |
(c) 5C |
(d) |
A moving coil sensitive galvanometer gives at once much more deflection. To control its speed of deflection
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(a) A high resistance is to be connected across its terminals |
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(b) A magnet should be placed near the coil |
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(c) A small copper wire should be connected across its terminals |
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(d) The body of galvanometer should be earthed |
