Two flat planes of glass are laid on top of one another.The upper plane is slightly raised due to the insertion of a thin piece of paper at one end and an air wedge is thus formed.Light of wavelength 500 nm is normally incident on the glass from above and interference fringes are observed by reflection with 2.5 fringes per cm.Calculate the angle of the wedge. A)6.3 $\times$ 10^-5 deg B)1.8 $\times$ 10^-3 deg C)4.0 $\times$ 10^-4 deg D)3.6 $\times$ 10^-3 deg E)5.7 $\times$ 10^-4 deg

Question

Quizplus · Accepted Answer

The formula for the angle of the wedge is given by:

θ = λ / (2d * n)

Where λ is the wavelength of the light, d is the distance between adjacent fringes (which is the inverse of the fringe density), and n is the index of refraction of the glass.

We are given that the fringe density is 2.5 fringes per cm, which means that d = 1 / (2.5 fringes/cm) = 0.4 cm.

The index of refraction of glass is typically around 1.5.

Plugging in these numbers, we get:

θ = (500 nm) / (2 * 0.4 cm * 1.5)
θ = 3.6 degrees

Therefore, the answer is (D), 3.6 degrees.

Two Flat Planes of Glass Are Laid on Top of One