In a Young’s double slit experiment, the source illuminating the slits is changed from blue to violet. The width of the fringes
|
(a) Increases |
(b) Decreases |
(c) Becomes unequal |
(d) Remains constant |
(b) Decreases
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A rectangular coil ABCD is rotated anticlockwise with a uniform angular velocity about the axis shown in diagram below. The axis of rotation of the coil as well as the magnetic field B are horizontal. The induced e.m.f. in the coil would be maximum when
| (a) The plane of the coil is horizontal |
|
(b) The plane of the coil makes an angle of 45° with the magnetic field |
|
(c) The plane of the coil is at right angles to the magnetic field |
|
(d) The plane of the coil makes an angle of 30° with the magnetic field |
Assertion : Radioactive nuclei emit 
particles.
Reason : Electrons exist inside the nucleus.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Assertion : The threshold frequency of photoelectric effect supports the particle nature of sunlight.
Reason : If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
An X-ray has a wavelength of 0.010 Å. Its momentum is
| (a) 2.126 × 10–23 kg-m/sec | (b) 6.626 × 10-22 kg-m/sec |
| (c) 3.456 × 20–25 kg-m/sec | (d) 3.313 × 10–22 kg-m/sec |
The heat developed in an electric wire of resistance R by a current I for a time t is
|
(a) |
(b) |
(c) |
(d) |
Which of the following electromagnetic waves have minimum frequency
|
(a) Microwaves |
(b) Audible waves |
(c) Ultrasonic waves |
(d) Radiowaves |
The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of volts is equal to
(a) 
|
(b) 
|
(c) 
|
(d) 
|
