Question

Suppose our apparatus will only allow us to distinguish the first order bright fringe from the central bright spot if they are separated by at least 5º. Find the shortest wavelength of light for which this apparatus is useful

Answer 1

Answer:

λ = 8.716 mm

Explanation:

Given:

- d = 10 cm

- Q >= 5 degrees

Find:

- Find the shortest wavelength of light for which this apparatus is useful

Solution:

- The formula that relates the split difference and angle of separation between successive fringes is given by:

                                            d*sin(Q) = n*λ

Where,

λ: wavelength

d: split separation

Q: angle of separation between successive fringes

m: order number.

- Since this apparatus only shows the first order light so m =1

- the shortest possible wavelength corresponds to:

                                            d*sin(Q) = λ

                                            λ = 0.1*sin(5)

                                            λ = 8.716 mm