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Two plane mirrors are inclined at an angle of 72° . The number of images of a point object placed between them will be
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(a) 2 |
(b) 3 |
(c) 4 |
(d) 5 |
There is no couple acting when two bar magnets are placed coaxially separated by a distance because
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(a) There are no forces on the poles |
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(b) The forces are parallel and their lines of action do not coincide |
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(c) The forces are perpendicular to each other |
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(d) The forces act along the same line |
In the diagram a graph between the intensity of X-rays emitted by a molybdenum target and the wavelength is shown, when electrons of 30 keV are incident on the target. In the graph one peak is of 
line and the other peak is of 
line
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(a) First peak is of |
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(b) Highest peak is of Ka line at 0.7 Å |
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(c) If the energy of incident particles is increased, then the peaks will shift towards left |
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(d) If the energy of incident particles is increased, then the peaks will shift towards right |
A galvanometer with a resistance of 12 W gives full scale deflection when a current of 3 mA is passed. It is required to convert it into a voltmeter which can read up to 18 V. the resistance to be connected is
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(a) 6000 W |
(b) 5988 W |
(c) 5000 W |
(d) 4988 W |
In extrinsic semiconductors
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(a) The conduction band and valence band overlap |
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(b) The gap between conduction band and valence band is more than 16 eV |
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(c) The gap between conduction band and valence band is near about 1 eV |
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(d) The gap between conduction band and valence band will be 100 eV and more |
The number of turns of primary and secondary coils of a transformer are 5 and 10 respectively and the mutual inductance of the transformer is 25 henry. Now the number of turns in the primary and secondary of the transformer are made 10 and 5 respectively. The mutual inductance of the transformer in henry will be
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(a) 6.25 |
(b) 12.5 |
(c) 25 |
(d) 50 |