10 wires (same length, same area, same material) are connected in parallel and each has 1 Ω resistance, then the equivalent resistance will be
|
(a) 10 Ω |
(b) 1 W |
(c) 0.1 W |
(d) 0.001 W |
(c) 0.1 W
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Assertion : The quantity L/R possesses dimensions of time.
Reason : To reduce the rate of increases of current through a solenoid should increase the time constant (L/R).
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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 resistivity of iron is 1
. The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in ohm - m will be
|
(a) |
(b) 2 |
(c) 4 |
(d) 8 |
A bulb of 100 watt is hanging at a height of one meter above the centre of a circular table of diameter 4 m. If the intensity at a point on its rim is 
, then the intensity at the centre of the table will be
|
(a) |
(b) 2 |
(c) 2 |
(d) 5 |
The energy of a photon of light with wavelength 5000 Å is approximately 2.5 eV. This way the energy of an X-ray photon with wavelength 1Å would be
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(a) 2.5/5000 eV |
(b) |
(c) 2.5 × 5000 eV |
(d) |
A magnifying glass is used to read the newspaper. As it is moved far away from the newspaper:
If a proton is projected in a direction perpendicular to a uniform magnetic field with velocity v and an electron is projected along the lines of force, what will happen to proton and electron
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(a) The electron will travel along a circle with constant speed and the proton will move along a straight line |
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(b) Proton will move in a circle with constant speed and there will be no effect on the motion of electron |
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(c) There will not be any effect on the motion of electron and proton |
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(d) The electron and proton both will follow the path of a parabola |
When air in a capacitor is replaced by a medium of dielectric constant K, the capacity
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(a) Decreases K times |
(b) Increases K times |
(c) Increases |
(d) Remains constant |
