Question

Here are qualitative questions about waves.

(b) In the phenomenon of the double-slit interference, what is the qualitative effect on the spacing of the bright spots (and dark bands) if the wavelength of the light is decreased? (Do the spots get closer together or farther apart?)

(c) In the phenomenon of the double-slit interference, what is the qualitative effect on the spacing of bright spots (and dark bands) if the slit separation is decreased? (Do spots get closer together or farther apart?)

(d) In the phenomenon of the double-slit interference, what is the qualitative effect on the spacing of the bright spots (and dark bands) if the slit-to-screen distance is increased ?

Answer 1

Where, beta is the fringe width (distance between bright spots)

lambda is the wavelength of the light

D is the slit-to-screen distance

d is the slit separation

From this formula we can find the answers for these 3 questions.

b) If the wavelength of the light(lambda) is decreased, the distance between the bright spots(beta) also decreases. The spots get closer.

c) If the slit separation(d) is decreased, the distance between bright spots increases. The bright spots get farther apart.

d) If the slit-to-screen distance(D) is increased, the distance between bright spots increases. The bright spots get farther apart.