Question

Monochromatic light passes through two narrow slits 0.36 mm apart and forms an interference pattern on a screen 2.65 m away. If light of wavelength 632.69 nm is used, what is the distance from the center of the central maximum to the center of the third order bright fringe in centimeters?

Answer 1

Let's name some variables:

d: slit distance (in m); d = 0.00036 m

D: distance to the screen where the interference pattern is shown; D = 2.65 m

λ: wavelength of light; λ = 632.69 nm

y: distance from the center of the central maximum to the center of the third order bright fringe; we are solving for this

Given these known and unknown variables, we can use the following equation to solve for the unknown:

y = 3λD/d

Now, we just need to plug in the known variables:

y = 3*632.69*2.65/0.00036

y = 13971904.2 nm = 13.9719042 mm = 1.397 cm