A solid metallic sphere has a charge +3Q. Concentric with this sphere is a conducting spherical shell having charge -Q. The radius of the sphere is a and that of the spherical shell is b(b > a). What is the electric field at a distance R(a < R < b) from the centre
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(a) |
(b) |
(c) |
(d) |
(c) 
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Assertion : A metallic shield in form of a hollow shell may be built to block an electric field.
Reason : In a hollow spherical shield, the electric field inside it is zero at every point.
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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. |
A mark at the bottom of a liquid appears to rise by 0.1 m. The depth of the liquid is 1 m. The refractive index of the liquid is
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(a) 1.33 |
(b) |
(c) |
(b) 1.5 |
The equivalent resistance and potential difference between A and B for the circuit is respectively
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(a) 4 W, 8 V |
(b) 8 W, 4 V |
(c) 2 W, 2 V |
(d) 16 W, 8 V |
When a slow neutron goes sufficiently close to a 
nucleus, then the process that takes place is
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(a) Fission of |
(b) Fusion of neutron |
(c) Fusion of |
(d) First (a) then(b) |
The rays of different colours fail to converge at a point after going through a converging lens. This defect is called:
