Question

Two narrow slits separated by 1.1 mm are illuminated by 544-nm light.

Part A

Find the distance between adjacent bright fringes on a screen 5.5 m from the slits.

Express your answer to two significant figures and include the appropriate units.

Answer 1

For constructive interference, the path difference is a multiple of the wavelength:

dsintheta = m*lambda

m = 0 , 1 , 2 , 3 ......

location on the screen from

y = L*tantheta

for small angles

sintheta = tantheta

y = L*lambda*m/d

for adjacent fringes = m = 1

y = L*lambda*dm/d

d = 1.1 x 10^-3

lambda =544 x 10^-9 m

L = 5.5 m

y = 2.7 x 10^-3 m = 2.7 mm