The electric field inside a spherical shell of uniform surface charge density is
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(a) Zero |
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(b) Constant, less than zero |
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(c) Directly proportional to the distance from the centre |
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(d) None of the above |
(a) Zero
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A manufacturer uses a concave lens instead of a convex lens in a magnifying glass by mistake. What will be the effect on the working of the lens?
Assertion : A paramagnetic sample display greater magnetisation (for the same magnetising field) when cooled.
Reason : The magnetisation does not depend on temperature.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(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 the assertion and reason both are false. |
If scattering particles are 56 for 90° angle then this will be at 60° angle
|
(a) 224 |
(b) 256 |
(c) 98 |
(d) 108 |
Two positive point charges of 12 μC and 8 μC are 10cm apart. The work done in bringing them 4 cm closer is
|
(a) 5.8 J |
(b) 5.8 eV |
(c) 13 J |
(d) 13 eV |
A thin rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is T ¢, then ratio 
is
|
(a) |
(b) |
(c) |
(d) 2 |
Variation of current passing through a conductor as the voltage applied across its ends as varied is shown in the adjoining diagram. If the resistance (R) is determined at the points A, B, C and D, we will find that
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(a) RC = RD |
(b) RB > RA |
(c) RC > RB |
(d) None of these |
Assertion : The specific charge of positive rays is not constant.
Reason : The mass of ions varies with speed.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(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. |
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(d) If the assertion and reason both are false. |
The velocity of light emitted by a source S observed by an observer O, who is at rest with respect to S is c. If the observer moves towards S with velocity v, the velocity of light as observed will be
|
(a) c + v |
(b) c - v |
(c) c |
(d) |
