Two different metals are joined end to end. One end is kept at constant temperature and the other end is heated to a very high temperature. The graph depicting the thermo e.m.f. is
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(a)
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(b)
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(c)
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(d)
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(d)
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When germanium is doped with phosphorus, the doped material has
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(a) Excess positive charge |
(b) Excess negative charge |
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(c) More negative current carriers |
(d) More positive current carriers |
Assertion : De-morgan's theorem 
may be explained by the following circuit
Reason : In the following circuit, for output inputs ABC are 101
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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 ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is
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(a) 1/2 |
(b) 2/137 |
(c) 1/137 |
(d) 1/237 |
An electric dipole is kept in non-uniform electric field. It experiences
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(a) A force and a torque |
(b) A force but not a torque |
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(c) A torque but not a force |
(d) Neither a force nor a torque |
A beam of light AO is incident on a glass slab (μ = 1.54) in a direction as shown in figure. The reflected ray OB is passed through a Nicol prism on viewing through a Nicole prism, we find on rotating the prism that
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(a) The intensity is reduced down to zero and remains zero |
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(b) The intensity reduces down some what and rises again |
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(c) There is no change in intensity |
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(d) The intensity gradually reduces to zero and then again increases |
Image formed by a concave mirror of focal length 6 cm, is 3 times of the object, then the distance of object from mirror is
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(a) – 4 cm |
(b) 8 cm |
(c) 6 cm |
(d) 12 cm |
The e.m.f. of a cell is E volts and internal resistance is r ohm. The resistance in external circuit is also r ohm. The p.d. across the cell will be
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(a) E/2 |
(b) 2E |
(c) 4E |
(d) E/4 |
A lamp emits monochromatic green light uniformly in all directions. The lamp is 3% efficient in converting electrical power to electromagnetic waves and consumes 100W of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of 10m from the lamp will be
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(a) 1.34 V/m |
(b) 2.68 V/m |
(c) 5.36 V/m |
(d) 9.37 V/m |
