Interference and Young’s Experiment – Practice


1) Light of wavelength 540nm is incident on a pair of vertical slits. The distance between the centre of the two slits is 0.0426mm. The screen is placed 0.860 m from the slits. What is the distance from the central maximum to the first-order bright spot on the screen?

2) Green laser light is directed through a pair of thin slits that are 25 µm apart. The slits are 1.5 m from a screen on which bright fringes are 3.3 cm apart. Calculate the wavelength of the green laser light in nm.

3) A laser produces light with a wavelength of 720 nm. The light falls on parallel, vertical slits that are 25µm apart, an interference pattern is observed on a screen 1.45m away. The pattern shows a series of bright and dark bands.

a) Determine the angle of the first-order maximum, and the distance on the screen of that maximum from the central maximum.

b) Determine the distance from the central maximum to the third-order maximum.

Quick Answers:

1) 0.011m (1.1cm)

2) 550nm

3a) 1.65°     b) 0.125m (12.5cm)

Worked Answers: