Home
Class 12
PHYSICS
Two plane mirrors, a source S of light, ...


Two plane mirrors, a source S of light, wmitting monochromatic rays of wavelength `lamda` and a screen are arranged as shown in figure. If angle `theta` is very small, calculate fringe width of the interference pattern formed by reflected rays.

Text Solution

Verified by Experts

The correct Answer is:
`(2(a+b)lamda)/(4atheta)`

Distance between two sources `S_(1)` and `S_(2)` `d=2xx2acosthetasintheta=2asin2theta`
Screen distance `D=b+2acos^(2)theta`
`beta=(lamdaD)/(d)=(lamda(b+2acos^(2)theta))/(2asin2theta)=(lamda(b+2a))/(4atheta)`
(if `theta` is very much small)
Promotional Banner

Topper's Solved these Questions

  • WAVE OPTICS

    ALLEN|Exercise Exercise 5 A (Previous Years Questions)|17 Videos

  • WAVE OPTICS

    ALLEN|Exercise Exercise 5 B (Previous Years Questions)|19 Videos

  • WAVE OPTICS

    ALLEN|Exercise Exercise 4 A (Conceptual subjective Exercise)|9 Videos

  • UNIT & DIMENSIONS, BASIC MATHS AND VECTOR

    ALLEN|Exercise Exercise (J-A)|7 Videos

Similar Questions

Explore conceptually related problems

Two plane mirrors, a source S of light, emitting wavelengths of lambda_(1) = 4000overset(@)A" and" lambda_(2) = 5600overset(@)A and a screen are arranged as shown in figure. The angle theta shown is 0.05 radian and distance a and b are 1 cm and 38 cm respectively. (a) Find the fringe width of interference pattern formed on screen by the blue light. (b) Calculate the distance of first black line from central bright fringe. (c) Find the distance between two black lines which are nearest to the central bright fringe.

A ray of light is reflected by two perpendicular plane mirrors as shown. The angle theta is equal to:

Two monochromatic sources of light A and B of wavelengths 5500 Å and 4400 Å respectively are used simultanesouly to produce interference bands on a screen. Which orders of the fringes in the two interference patterns will coincide?

Two plane mirror inclined at an angle of 60° as shown in the figure, then the angle between the incident ray and the first reflected ray is_____°

A Lloyd's mirror or length 5 cm is illuminated with mon ochromatic light of wavelength lambda (= 6000 Å) from a narrow 1 mm slit in its plane and 5 cm plane from its near edge. Find the fringe width on a screen 120 cm from the slit and width of interference pattern on the screen.

Light incidence on a sphere of refractive index sqrt3 placed in a air as shown in Figure. Find the angle (theta) in degree between emergent ray and reflected ray.