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

Step-by-step explanation:

distance between two slit d =
`(1 * 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 =
`(\lambda)/(18.15*10^(-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 *\ 5*\ 10^ {-7}}{18.15*10^(-7)}`

=
`(2*5)/(18.5)`

θ = 28.4 degree .