A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance. The magnetic field at P is
| (a) Greater than at Q |
| (b) Same as at Q |
| (c) Less than at Q |
| (d) Greater or less than at Q depending upon the strength of the current |
(b) Same as at Q
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Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity
|
(a) Decreases |
(b) Increases |
(c) Remains unchanged |
(d) Becomes zero |
The depletion layer in silicon diode is 1 mm wide and the knee potential is 0.6 V, then the electric field in the depletion layer will be
|
(a) Zero |
(b) 0.6 Vm–1 |
(c) 6 × 104 V/m |
(d) 6 × 105 V/m |
An object of size 7.5 cm is placed in front of a convex mirror of radius of curvature 25 cm at a distance of 40 cm The size of the image should be
|
(a) 2.3 cm |
(b) 1.78 cm |
(c) 1 cm |
(d) 0.8 cm |
The ratio of intensities of two waves are given by 4 : 1. The ratio of the amplitudes of the two waves is
|
(a) 2 : 1 |
(b) 1 : 2 |
(c) 4 : 1 |
(d) 1 : 4 |
The variation of magnetic susceptibility (x) with temperature for a diamagnetic substance is best represented by
|
(a)
|
(b)
|
(c)
|
(d)
|
A sensitive magnetic instrument can be shielded very effectively from outside magnetic fields by placing it inside a box of
|
(a) Teak wood |
(b) Plastic material |
|
(c) Soft iron of high permeability |
(d) A metal of high conductivity |
The refractive index of water is 1.33. The direction in which a man under water should look to see the setting sun is
|
(a) 49o to the horizontal |
(b) 90o with the vertical |
|
(c) 49o to the vertical |
(d) Along the horizontal |
In Fresnel’s biprism (μ = 1.5) experiment the distance between source and biprism is 0.3 m and that between biprism and screen is 0.7m and angle of prism is 1°. The fringe width with light of wavelength 6000 Å will be
|
(a) 3 cm |
(b) 0.011 cm |
(c) 2 cm |
(d) 4 cm |
In terms of Rydberg's constant R, the wave number of the first Balmer line is
|
(a) R |
(b) 3R |
(c) |
(d) |
