Question

An interference pattern from a two-slit experiment with light has a spacing between the central (brightest) peak and the neighboring peak of 3.3 mm. The distance from the slits to the screen is 1.5 m and the wavelength of the light is 690 nm.

a) What is the angle between the central maximum and its neighbor? Express your answer in degrees.  

b) What is slit spacing, d? Please give this distance in millimeters.  

Answer 1

Part a

Angle theta

= tan inverse (y/D)

= tan inverse (3.3*10^(-3) / 1.5)

= tan inverse (2.2*10^(-3))

= 0.126 degrees

Part b

For interference,

d* sintheta = m*lambda

Thus, d = m*lambda / sintheta

= 1* 690*10^(-9) / sin0.126

= 0.0003137 m

= 0.3137 mm

Thanks