- ARadially outward.
- BRadially inward.
- CBoth a and b.
- DNone.
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The coil of dynamo is rotating in a magnetic field. The developed induced e.m.f. changes and the number of magnetic lines of force also changes. Which of the following condition is correct
|
(a) Lines of force minimum but induced e.m.f. is zero |
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(b) Lines of force maximum but induced e.m.f. is zero |
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(c) Lines of force maximum but induced e.m.f. is not zero |
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(d) Lines of force maximum but induced e.m.f. is also maximum |
In case of linearly polarized light, the magnitude of the electric field vector :
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(a) Does not change with time |
|
(b) Varies periodically with time |
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(c) Increases and decreases linearly with time |
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(d) Is parallel to the direction of propagation |
The binding energy of the innermost electron in tungsten is 40 keV. To produce characteristic X-rays using a tungsten target in an X-rays tube the potential difference V between the cathode and the anti-cathode should be
|
(a) V< 40 kV |
(b) V ≤ 40 kV |
(c) V > 40 kV |
(d) V >/< 40 kV |
An electron initially at rest, is accelerated through a potential difference of 200 volt, so that it acquires a velocity 8.4
. The value of e/m of electron will be
|
(a) 2.76 |
(b) 1.76 |
(c) 0.76 |
(d) None of these |
The true statement for thermo e.m.f. of a thermocouple
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(a) Depends on the nature of metals |
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(b) Depends only on temperature of cold junction |
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(c) Depends only on temperature of hot junction |
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(d) Depends on the length of the wires used for thermocouple |
The material of fuse wire should have
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(a) A high specific resistance and high melting point |
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(b) A low specific resistance and low melting point |
|
(c) A high specific resistance and low melting point |
|
(d) A low specific resistance and a high melting point |
If the distance of the far point for a myopia patient is doubled, the focal length of the lens required to cure it will become
|
(a) Half |
(b) Double |
|
(c) The same but a convex lens |
(d) The same but a concave lens |