Youngs Double Slit Experiment

In Young's double slit experiment, the fringe separation is inversely proportional to the wavelength . Since the fringe separation is given by: Where: - is the wavelength of light, - is the distance from the slits to the screen, - is the distance between the slits. The number of fringes per cm is the reciprocal of the fringe separation, so: For two different wavelengths and , we have the relationship: Given that and , the number of fringes with is: Thus, the number of fringes per cm with is 12.

The number of fringes per unit length is inversely proportional to the wavelength : Thus, the ratio of the number of fringes for the two wavelengths is: Substituting the values: Solving for : Thus, the number of fringes per cm is 12 for the wavelength 7000 Ã….

Concept: In Young's Double Slit Experiment (YDSE), the fringe width is given by: where:

• = wavelength of light
• = distance between slits and screen
• = distance between the two slits

Thus, fringe width is:
Step 1: {Write the original fringe width.}
Step 2: {Apply the given changes.} Distance between slits is doubled: Screen distance is halved:
Step 3: {Substitute into the fringe width formula.}
Step 4: {Compare with original fringe width.} Thus, the fringe width becomes one-fourth of the original value.