Question

Double Slit Interference

Data

d = 0.4mm or 4*10^-3m (using calipers)

ƛ = 532.nm or 532 *10^-9m

L = 36cm or 36*10^-2m

∆y = 0.45cm or 45*10^-2m

Calculation d = 8.62*10^-2

1. Describe what you could have done to improve the accuracy of your measurements.

2. Examine the measuring equipment you used and determine which equipment limited you the most on the precision of your calculations.

3. How would adjusting the distance between the double slit aperture and the screen affect your measurements?

4. How would adjusting the distance between the light source and the aperture affect your measurements?

5. How would your observations change if you used red laser light, but used the same double-slit aperture and screen distance? What would you observe?

Answer 1

1) We can improve the accuracy of our measurements by controlling all the variables. We should make sure that our successive readings do not differ much and the measuring device is calibrated to required decimal places.

3) We know that in double slit interference

fringe width = lambda*D / d where d is distance between slits, D - distance between slit (aperture) and screen. Now if we are changing the D ( distance between slit and screen), the fringe width will change accordingly. If we increase D, width will increase and if we decrease D, width will decrease.

4) if we vary the distance between light source and slit, the focus of the fringes will change. It will also affect the intensity of the pattern and amount of light passing through the aperture will change.

5) Now as we can see from the formula, red light ( it has the highest wavelength) will increase the fringe width ( linear width).