The magnet can be completely demagnetized by
|
(a) Breaking the magnet into small pieces |
|
(b) Heating it slightly |
|
(c) Droping it into ice cold water |
|
(d) A reverse field of appropriate strength |
(d) A reverse field of appropriate strength
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The binding energy of deuteron 
is 1.112 MeV per nucleon and an α - particle 
has a binding energy of 7.047 MeV per nucleon. Then in the fusion reaction 
the energy Q released is
|
(a) 1 MeV |
(b) 11.9 MeV |
(c) 23.8 MeV |
(d) 931 MeV |
Which of these is unipolar transistor
|
(a) Point contact transistor |
(b) Field effect transistor |
| (c) PNP transistor | (d) None of these |
Which source is associated with a line emission spectrum
|
(a) Electric fire |
(b) Neon street sign |
(c) Red traffic light |
(d) Sun |
On increasing the temperature of a conductor, its resistance increases because
|
(a) Relaxation time decreases |
(b) Mass of the electrons increases |
|
(c) Electron density decreases |
(d) None of the above |
The energy of a photon of characteristic X-rays from a Coolidge tube comes from
| (a) The kinetic energy of the striking electron |
| (b) The kinetic energy of the free electrons of the target |
| (c) The kinetic energy of the ions of the target |
| (d) An electronic transition of the target atom |
The mutual inductance between two coils is 1.25 henry. If the current in the primary changes at the rate of 80 ampere/second, then the induced e.m.f. in the secondary is
|
(a) 12.5 V |
(b) 64.0 V |
(c) 0.016 V |
(d) 100.0 V |