Question

Two slits are illuminated by a 540 nm light. The angle between the zeroth-order bright band at the center of the screen and the fourth-order bright band is 13.5?.

If the screen is 160 cm from the double-slit, how far apart is this bright band from the central peak? Answer in cm.

Answer in units of cm.

Answer 1

Here, we have to find the value of the distance between bright band from the central peak

Let's assume that the separation of the slit is smaller than the distance between slits and screen, So, we can say that sin is equalled to tan

Where tan = Y(n)/D

Where D = distance to the screen = 160 cm,

Y(n) = nth order maximum as n = 4 so it is Y (4)

= 13.5 degree

Therefore we have

Y(4) = D* tan

Y(4) = 160 * tan (13.5 degree)

Y(4) = 38.41 cm (The distance between bright band and central peak)