CBSE
Multiple Choice QuestionsAn em wave is propagating in a medium with a velocity . The instataneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along
-z direction
+z direction
-x direction
-y-direction
The tip of a needle does not give a sharp image on a screen. This is due to
polarisation
interference
diffraction
None of these
Light of wavelength 6000 A0 is reflected at nearly normal incidence from a soap film of refractive index 1.4. The least thickness of the film that will appear black is
200 A0
2000 A0
1000 A0
Infinity
Two coherent light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are
5I and I
5 I and 3 I
9 I and I
9 I and 3 I
Two coherent light beams of intensities I and 41 are superposed. The maximum and minimum possible intensities in the resulting beam are
5I and I
5I and 3I
9I and I
9I and 3I
Light travels faster in air than that in glass .This is accordance with
wave theory of light
corpuscular theory of light
Neither(a) nor(b)
Both (a) and (b)
The maximum numbers of possible interference maxima for slit separation equal to twice the wavelength in Young's double slit experiment is
infinite
five
three
zero
In Young's double slit experiment, light of wavelength 6000 A0 is used to produced fringes of width 0.8 mm at a distance of 2.5 m. If the whole appart is dropped in liquid of refractive index 1.6, then the fringe width will be
0.2mm
0.4mm
0.5mm
0.6mm
If prism angle α = 1o , μ= 1.54, distance between screen and prism (D) = 0. 7 m, distance between prism and source nm, then in Fresnal biprism find the value of β (fringe width).
10-4 m
10-3 mm
10-4 × m
Interference was observed in an interference chamber when air was present. Now, the chamber is evacuated and if the same light is used, a careful observation will show
no interference
interference with bright band
interference with dark bands
interference in which breadth of the fringe will be slightly increased
