How do you calculate wavelength in Newton's ring experiment?

Answer 1

The condition for constructive interference in thin filmis,

m = 0,1,2,....

From equation (1) putting the value of t in the above equation we get,

since n = 1 for air film

or

For first bright ring, m = 0

For second bright ring, m = 1

For third bright ring, m = 2

Similarly, for Nth bright ring,

m = N - 1

Radius for dark ring

The condition for destructive interference in thin filmis,

2tn = mλ m = 0,1,2,....

By putting the value of t, we get,

For air n = 1

For i.e. point of contact.

Answer 2

by substitue the values of R,D