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

Answer:

Wavelength of light will be 632.73 nm

Explanation:

We have given width of the single slit $d=1850nm-1850\times 10^{-9}m$

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 $1850\times 10^{-9}\times sin20^{\circ} =1\times \lambda$

$\lambda =632.73nm$