Question

What causes the bright and dark fringes to appear on the screen in a double slit interference experiment?

m#2 m-1 m 2 mA screen igure 2. Description of a double slit interference pattern. Peaks represent bright spots. The constructive interference when the distances from the first slit to the screen and the second slit to the screen differ by a whole wavel ength than The two angles labeled theta can be considered equal when the distance to the screen, D, is much greater multiple. the slit separation. What causes the bright and dark fringes to appear on the sereen in a double slit interference experiment? in Figure 2 write down the trigonometric equation that relates slit separation, d, the Q8. From the diagram in Figure 2 write down an expression for tan 0 in terms of the distance from the slits Q9. Using your answers from questions 7-8, derive an approximate formula for the slit separation, d, in angle, θ, the wavelength of the light, λ, and the order, m. to the screen, D, and the distance from the center of the pattern to the mth maximum, y. terms of D, y, λ, and m. what approximation did you make? Q10. Why is this equation very similar to the one describing diffraction?

Answer 1

Path difference between rays of light reach to a point on screen from two slit causes the bright and dark fringes or we can say the constructive and destructive interference are the causes of bright and dark fringes.

If path difference is zero or integral multiple of wavelength the there will be constructive interference and bright fringes will be formed.

If path difference is integral multiple of half of wavelength the there will be destructive interference and dark fringes will be formed.