An 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 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
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
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)
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
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
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
The tip of a needle does not give a sharp image on a screen. This is due to
polarisation
interference
diffraction
None of these
C.
diffraction
As the size of tip of the needle is very small ( because its a point ) and it comes under the range of wavelength of light, so the ray coming from back side of needle ( i.e consider needle's tip just blocking a ray of light) will bend across the tip.
And hence on screen, that ray will also give brightness near so formed image of needle's tip, hence reducing the original sharpness of the needle's tip.
The tip of a needle does not give a sharp image, it is due to diffraction.
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
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