If the critical angle for total internal reflection from a medium to vacuum is 30°, the velocity of light in the medium is
|
(a) 3 |
(b) 1.5 |
(c) 6 |
(d) |
(b) 1.5 
m/s
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A bar magnet is oscillating in the earth's magnetic field with time period T. If its mass is increased four times then its time period will be
|
(a) 4 T |
(b) 2T |
(c) T |
(d) T/2 |
There is a current of 20 amperes in a copper wire of 
square metre area of cross-section. If the number of free electrons per cubic metre is 
, then the drift velocity is
|
(a) 125 |
(b) 12.5 |
(c) 1.25 |
(d) 1.25 |
An electric dipole is kept in non-uniform electric field. It experiences
|
(a) A force and a torque |
(b) A force but not a torque |
|
(c) A torque but not a force |
(d) Neither a force nor a torque |
Polarising angle for water is 53°4'. If light is incident at this angle on the surface of water and reflected, the angle of refraction is
|
(a) 53°4' |
(b) 126°56' |
(c) 36°56' |
(d) 30°4' |
A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is from left to right then what will be the effect on electron stream
|
(a) The electron stream will be pulled upward |
|
(b) The electron stream will be pulled downward |
|
(c) The electron stream will be retarted |
|
(d) The electron beam will be speeded up towards the right |
The resistance of a reverse biased P-N junction diode is about
|
(a) 1 ohm |
(b) |
(c) |
(d) |
The dependence of binding energy per nucleon, 
on the mass number, A, is represented by
|
(a)
|
(b)
|
(C)
|
(d)
|
If the amplitude ratio of two sources producing interference is 3 : 5, the ratio of intensities at maxima and minima is
|
(a) 25 : 16 |
(b) 5 : 3 |
(c) 16 : 1 |
(d) 25 : 9 |
Rate of change of torque τ with deflection θ is maximum for a magnet suspended freely in a uniform magnetic field of induction B, when
| (a) θ = 0° | (b) θ = 45° | (c) θ = 60° | (d) θ = 90° |
