The essential distinction between X-rays and γ - rays is that
| (a) γ- rays have smaller wavelength than X-rays |
|
(b) γ - rays emanate from nucleus while X-rays emanate from outer part of the atom |
| (c) γ- rays have greater ionizing power than X-rays |
| (d) γ- rays are more penetrating than X-rays |
(b) γ - rays emanate from nucleus while X-rays emanate from outer part of the atom
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200 MeV of energy may be obtained per fission of 
. A reactor is generating 1000 kW of power. The rate of nuclear fission in the reactor is
|
(a) 1000 |
(b) 2 |
(c) 3.125 |
(d) 931 |
A two metre wire is moving with a velocity of 1 m/sec perpendicular to a magnetic field of 0.5 weber/m2. The e.m.f. induced in it will be
|
(a) 0.5 volt |
(b) 0.1 volt |
(c) 1 volt |
(d) 2 volt |
When radiation of wavelength 
is incident on a metallic surface, the stopping potential is 4.8 volts. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes 1.6 volts. Then the threshold wavelength for the surface is
|
(a) 2 |
(b) 4 |
(c) 6 |
(d) 8 |
$\text{x}=\text{A}\sin(\text{ky}-\omega\text{t})$
$\text{y}=\text{A}\sin(\text{kx}-\omega\text{t})$
$\text{y}=\text{A}\sin\text{ky}\cos\ \omega\text{t}$
$\text{y}=\text{A}\cos\text{ky}\sin\ \omega\text{t}.$
A concave mirror is used to focus the image of a flower on a nearby well 120 cm from the flower. If a lateral magnification of 16 is desired, the distance of the flower from the mirror should be
|
(a) 8 cm |
(b) 12 cm |
(c) 80 cm |
(d) 120 cm |
A charge of Q coulomb is placed on a solid piece of metal of irregular shape. The charge will distribute itself
|
(a) Uniformly in the metal object |
|
(b) Uniformly on the surface of the object |
|
(c) Such that the potential energy of the system is minimised |
|
(d) Such that the total heat loss is minimised |
In the adjoining diagram, a wavefront AB, moving in air is incident on a plane glass surface XY. Its position CD after refraction through a glass slab is shown also along with the normals drawn at A and D. The refractive index of glass with respect to air (μ = 1) will be equal to
|
(a) |
(b) |
(c) |
(d) |
In the white light of sun, maximum scattering by the air molecules present in the earth's atmosphere is for:
