Question

A student is measuring maxima and minima on a screen due to coherent laser light (wavelength = 700 nm) incident upon two narrow slits. The two slits are seperated by a distance, d. The screen is 2.0 m away from the two slits. The student is suppose to measure the distance along the screen from a given maxima to the central maximum. The student mistakenly measure the distance along the screen, y from the m=+3 maxima on one side of the central maxima to m=-2 on the other side of the central maxima (shown in the picture). Dark spots correspond to minima and white spots correspond to maxima. What is the value of d if the student measure y to be 0.008m?

Please show you steps thoroughly.

Answer 1

Answer 2

y = m lambda L/d

3 to -2 means m = 5

0.008 = 5*700.0E-9*2/d

d=8.75E-4 m

Answer 3

y3 = 3 L lambda/d

y(-2) = -2 L lambda/d

y3 - y(-2) = 5 L lamda/d

==> 0.008 = (5 * 2 * 700e-9)/(d)

==> d = 8.75 x 10^-4 m