Question

A laser beam of unknown wavelength passes through adiffraction grating having 5510 lines/cm after striking itperpendicularly. Taking measurements, you find that the first pairof bright spots away from the central maximum occurs at±15.4° with respect to the original beam direction. (a) What is the wavelength of thelight? (b) at what angle will the next pair ofbright spots occur?

Answer 1

Answer:

Explanation:

distance between two slit  d = $\frac{1 \times 10^{-2}}{5510}$

d = 18.15 x 10⁻⁷ m

Let wave length of light λ

formula for  position of  first pair of bright spot

Tanθ = λ / d , λ is wave length of light and d is distance between two slit .

Tan 15.4 = $\frac{\lambda}{18.15\times10^{-7}}$

λ = Tan 15.4 x 18.15 x 10⁻⁷

=5 x 10⁻⁷ m

If θ be the position of next bright spot

Tanθ = 2 λ / d

= $\frac{2 \times\ 5\times\ 10^ {-7}}{18.15\times10^{-7}}$

=$\frac{2\times5}{18.5}$

θ = 28.4 degree .