Dynamo core is laminated because
|
(a) Magnetic field increases |
|
(b) Magnetic saturation level in core increases |
|
(c) Residual magnetism in core decreases |
|
(d) Loss of energy in core due to eddy currents decreases |
(d) Loss of energy in core due to eddy currents decreases
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One requires energy 
to remove a nucleon from a nucleus and an energy ‘
to remove an electron from the orbit of an atom. Then
|
(a) |
(b) |
(c) |
(d) |
A point object O is placed on the principal axis of a convex lens of focal length f = 20cm at a distance of 40cm to the left of it. The diameter of the lens is 10cm. An eye is placed 60cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is:
A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the current in the circuit will
| (a) Decrease | (b) Remain unchanged | (c) Increase | (d) Stop flowing |
Two magnets of same size and mass make respectively 10 and 15 oscillations per minute at certain place. The ratio of their magnetic moments is
| (a) 4 : 9 | (b) 9 : 4 | (c) 2 : 3 | (d) 3 : 2 |
The nuclear reaction 
(mass of deuteron = 2.0141 a.m.u. and mass of He = 4.0024 a.m.u.) is
|
(a) Fusion reaction releasing 24 MeV energy |
|
(b) Fusion reaction absorbing 24 MeV energy |
|
(c) Fission reaction releasing 0.0258 MeV energy |
|
(d) Fission reaction absorbing 0.0258 MeV energy |
The momentum of a photon in an X-ray beam of 
metre wavelength is
|
(a) 1.5 |
(b) 6.6 |
|
(c) 6.6 |
(d) 2.5 |
A uniform electric field and a uniform magnetic field are produced, pointed in the same direction. An electron is projected with its velocity pointing in the same direction
|
(a) The electron will turn to its right |
|
(b) The electron will turn to its left |
|
(c) The electron velocity will increase in magnitude |
|
(d) The electron velocity will decrease in magnitude |
