S. No |
Physical quantity |
Dependent or Independent |
Measured with |
Measuring instrument’s |
||
Minimum |
Maximum |
Least count |
||||
1 |
Slit width (\(d\)) |
Independent |
Micrometer |
0.01 mm | 0.01 mm | |
2 |
Distance between slit and screen (\(D\)) |
Independent |
Meter scale |
1 mm | 1000 mm | 1 mm |
3 |
Displacement (or position of maxima) on screen (\(x\)) |
Independent |
Vernier scale |
0.1 mm | 0.1 mm |
A. Intensity vs displacement on screen:-
Level the optical rail with the table.
Set up the laser diode and slit on the optical rail in proper alignment.
Fix the distance at which the screen should be from the slit.
Adjust slit width (and measure it using micrometer) and observe on the screen for a distinguishable diffraction pattern.
Set the photodetector at optimum height and check for highest intensity at central maximum.
Take intensity reading on detector as a function of displacement (measured using Vernier scale) on both sides.
B. Wavelength of light:-
Keeping the setup undisturbed, replace the photodetector with a screen.
Using the Vernier scale attached with screen, mark the positions of maxima till 5-7 orders on either side.
By calculating fringe width of different orders from the difference in positions of maxima, find the wavelength of light by taking average.