In Young's double slit experiment, the slits are 0.5 mm apart and interference pattern is observed on a screen placed at a distance of 1.0 m from the plane containing the slits. If wavelength of the incident light is 6000 Å, then the separation between the third bright fringe and the central maxima is
|
(a) 4.0 mm |
(b) 3.5 mm |
(c) 3.0 mm |
(d) 2.5 mm |
(b) 3.5 mm
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When photon of energy 4.25 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TA eV and de-Brolie wavelength 
. The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.70 eV is 
If the de-Broglie wavelength of these photoelectrons is 
, then
|
(a) The work function of A is 2.25 eV |
(b) The work function of B is 4.20 eV |
|
(c) |
(d) |
Hydrogen (H), deuterium (D), singly ionized helium (
and doubly ionized lithium (Li) all have one electron around the nucleus. Consider n =2 to n = 1 transition. The wavelengths of emitted radiations are 
and 
respectively. Then approximately
|
(a) |
(b) 4 |
|
(c) |
(d) |
Two straight horizontal parallel wires are carrying the same current in the same direction, d is the distance between the wires. You are provided with a small freely suspended magnetic needle. At which of the following positions will the orientation of the needle be independent of the magnitude of the current in the wires
|
(a) At a distance d/2 from any of the wires |
|
(b) At a distance d/2 from any of the wires in the horizontal plane |
|
(c) Anywhere on the circumference of a vertical circle of radius d and centre halfway between the wires |
|
(d) At points halfway between the wires in the horizontal plane |
Vibration magnetometer before use, should be set
| (a) In magnetic meridian | (b) In geographical meridian |
| (c) Perpendicular to magnetic meridian | (d) In any position |
The instrument that is based on the principle that when an object is placed between first principal focus and the optic centre of convex lens, an upright, virtual and enlarged image on the same side of the object is formed, is:
Magnification of an optical instrument is expressed in:
When current flows through a conductor, then the order of drift velocity of electrons will be
|
(a) |
(b) |
(c) |
(d) |
In a semiconductor
|
(a) There are no free electrons at any temperature |
|
(b) The number of free electrons is more than that in a conductor |
|
(c) There are no free electrons at 0 K |
|
(d) None of these |
