Explanation:
If white light is used a white centre fringe is observed, but all the other fringes have coloured edges, the blue edge being nearer the centre. Eventually the fringes overlap and a uniform white light is produced.
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A parallel beam of monochromatic light of wavelength 5000 Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to
|
(a) 0o |
(b) 15o |
(c) 30o |
(d) 60o |
Two capacitors of 10 μF and 20 μF are connected in series with a 30V battery. The charge on the capacitors will be, respectively
|
(a) 100 μC, 200 μC |
(b) 200 μC, 100 μC |
(c) 100 μC, 100 μC |
(d) 200 μC, 200 μC |
An ionized gas contains both positive and negative ions. If it is subjected simultaneously to an electric field along the +x direction and a magnetic field along the +z direction, then
|
(a) Positive ions deflect towards +y direction and negative ions towards –y direction |
|
(b) All ions deflect towards +y direction |
|
(c) All ions deflect towards –y direction |
|
(d) Positive ions deflect towards –y direction and negative ions towards +y direction |
Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand
| (a) None | (b) 1 | (c) 2 | (d) 3 |
A point source of light is placed at a distance, of 2f from a converging lens of focal length f. The intensity on the other side of the lens is maximum at a distance:
The wavelength of most energetic X-rays emitted when a metal target is bombarded by 40KeV electrons, is approximately (h = 6.63 
)
|
(a) 300 Å |
(b) 10 Å |
(c) 4 Å |
(d) 0.31 Å |