The Wave Nature of Light

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If you draw a line from each slit to the 1st order bright line, you will notice that one line is longer than the other.

The difference between these two lines is 1λ.

Destructive Interference
 

Constructive Interference causes ...      Bright Lines    Destructive Interference causes...      Dark Lines

Young's Double Slit Experiment Simulation

AP B Physics

Finding 2nd, 3rd, 4th
 .... order bright lines

q = angle between slits and line

d = distance between slits

m = 0, 1, 2, .... order bright lines

m = 1/2, 1 1/2, 2 1/2 dark lines

q =  angle to bright line

x/L = ml/d

x = distance from central maxima

Polarization

AP Physics

Ex) Calculate the distance between two slits in a Double Slit Experiment if the wavelength of the light used is is 5 x 10^-7 m and the distance between the central maximum and the first order bright line is 2 x 10^-2 m. The distance from the slits to the screen is 4 meters.

(5 x 10^-7 m)/d = (2 x 10^-2 m)/4 m


Answer d = 1 x 10^-4 m
 

Question: If they give you d, L and x and asked you to find the COLOR of the light used, What would you do? Where would you go to find the color?

Answer:

1. Solve for λ use Young's Equation

2. Use 3 x 10⁸ m/s = fλ to find the colors frequency

3. Look up the color on page 2 Ref.