Question

An instructor wishes to determine the wavelength of the light in a laser beam. To do so, he directs the beam toward a partition with two tiny slits separated by 0.195 mm. An interference pattern appears on a screen that lies 5.10 m from the slit pair. The instructor's measurements show that two adjacent bright interference fringes lie 1.55 cm apart on the screen. What is the laser's wavelength (in nm)

Answer 1

λ = 610.6 nm

Step-by-step explanation:

We are given;

Separation distance; d = 0.195 mm = 0.195 × 10^(-3) m

Interference pattern distance; D = 4.95 m

Width of the two adjacent bright interference; β = 1.55 cm = 1.55 × 10^(-2) m

Formula for the Fringe width is;

β = Dλ/d

Where;

λ is laser's wavelength

Thus;

λ = (d × β)/(D)

λ = (0.195 × 10^(-3) × 1.55 × 10^(-2))/4.95

λ = 610.6 × 10^(-9) m

λ = 610.6 nm