Perform Easy Young's Double Slit Experiment

Young's Double slit interference Experiment is a remarkable experiment in Physics which demonstrates the effects of particle-wave duality of light. LASER (Light Emission by Stimulated Emission of Radiation) light is a form of light which exhibits both particle and wave duality. Using a LASER light may be DANGEROUS as it may lead to eye damage, that is why, while doing this experiment, I wore glasses and kept the LASER away from pointing towards my eyes. I learned about this experiment in school and in order to expand my learning, I experimented myself. I have used a metal shaving blade and two old-school pencil leads to create a double-slit. In this experiment, the double slit should be small enough to accommodate both the holes.

Supplies

1. LASER Light - Type 1 - The safest one to use. Ask for a monochromatic light.
2. A cardboard box. - to hold the LASER in place.
3. A cardboard screen to project the pattern on.
4. A measuring paper - one with marking along centimeters or inches, if you don't have one, print out a large sheet with markings or you can also draw with hand.
5. Old pencil leads- they are very thin and small. I have used as shown in the picture.
6. Tape - to stick the LASER into place.
7. A cardboard box to hold the double - slit. I have used a smartphone box.
8. Electrical Tape -to mask the gaps and experiment with different slits. I have not used normal tape because it is transparent.

Step 1: Construct the LASER Box.

I have stuck the LASER onto a plastic box which is smaller in width and height to the containing cardboard box. I poked a hold right above the LASER button on the containing box to continuously press the button.

Step 2: Prepare the Slit Box

I have used a smartphone box to mark the slit place. Then, I cut a square piece out of the box to paste double slit in its place. I have done this to test different types of slits - single slit, double slit, even triple slit.

Step 3: Prepare the Slits

Use a pen to poke a hole into a thin cardboard piece. Stick the leads such that they are parallel, with a very small gap in-between them. Use two leads to create a single slit, use three leads. stick them close with a very minute gap, experiment with different gaps to come up with the best pattern. Then, use two pieces of shaving blade (DANGER: Ask your parents help for this) to reduce the side-gap from the leads to the hole in the cardboard. You can also use electrical tape to cover the rest of the area.

Step 4: Compose the Setup

I have used measuring paper to mark the places where each piece was setup. Then, i used the display board with the measuring paper. Mark the paper along the interference pattern to verify measurements.

Step 5: Verify Measurements

Make a note of the following important values:

1. Lambda = frequency of the LASER. (As mentioned on the box)
2. d = distance in between the slits = Diameter of the lead = 0.5mm (As mentioned on the box of Leads)
3. D = distance from the slit to the screen.
4. Beta = distance between the two peaks or two troughs.

Evaluate the following values, in my case

Lambda = 532nm

d = 0.5mm

D = 47cm

Beta_{Actual = 0.5cm}

Beta_{Measured = Lambda* D / d}

= 0.50008cm

Error = (Measured - Actual) * 100/ Actual

= 0.0008 * 100/ 0.5

= 0.000016 %

PS: Make sure the measurements are precise, keep the distance as long as possible.