Question

A He–Ne laser illuminates a narrow, single slit that is 1850 nm wide. The first dark fringe is found at an angle of 20.0∘ from the central peak. 1) Determine the wavelength of the light from the laser. (Express your answer to three significant figures.)

Answer 1

Wavelength of light will be 632.73 nm

Step-by-step explanation:

We have given width of the single slit
`d=1850nm-1850* 10^(-9)m`

Angle is given as
`\Theta =20^(\circ)`

We have to find the wavelength of light for first dark fringe

We know that for dark fringe it is given that

`dsin\Theta =n\lambda`

For first fringe n = 1

So
`1850* 10^(-9)* sin20^(\circ) =1* \lambda`

`\lambda =632.73nm`