KVPY2016PhysicsWave Optics
A monochromatic light source S of wavelength 440 ~nm is placed slightly above a plane mirror M as shown. Image of S in M can be used as a virtual source to produce interference fringes on the screen. The distance of source S from O is 20.0 ~cm , and the distance of screen from O is 100.0 ~cm (figure is not to scale). If the angle =0.50 10⁻³ radians, the width of the interference fringes observed on the screen is -
Options
- A2.20 ~mm
- B2.64 ~mm
- C1.10 ~mm
- D0.55 ~mm
Correct answer
B. 2.64 ~mm
Step-by-step solution
S and S _ I are source of YDSE =0.5 10⁻³ radian (very small) array l D = SO +100 =20 1+100 =120 ~cm ~d =2 SO 2 20 40 0.5 10⁻³ ~cm 2 10⁻² ~cm = D d = 440 10⁻⁶ 120 10² 2 10⁻² 10² 264 10⁻² 2.64 ~mm array