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When a student shines a 470 nm laser through this grating, how many bright spots could be seen on a screen behind the grating

Respuesta :

Manetho

Answer:

15

Explanation:

Assuming that commercial diffraction grating has 300 lines per mm.

also, given that a 470 nm laser through this grating

d = width of the slit  must be = [tex]\frac{10^{-3}}{300}[/tex]

λ = wavelength = 470 nm = 470 x 10^{-9} m

Using the equation

d Sinθ = nλ

n = order

N = number of spots

θ = angle between the diffracted ray and the normal ray= 90°

Assuming the incident ray to be normal to the surface

Plugging the values we get

[tex]3.33\times10^{-6}sin90 = n(470\times10^{-9})[/tex]

solving we get

n = 7

Number of spots are given as

N = 2n + 1

N = 2(7) + 1

N = 15

Cricetus

The number of bright spots will be "15".

Wavelength

According to the question,

Angle between the two rays, θ = 90°

Wavelength, λ = 470 nm or,

                        = 470 × 10⁻⁹ m

Width of slit, d = [tex]\frac{10^{-3}}{300}[/tex]

We know the formula,

→     d Sinθ = nλ

By substituting the values, we get

3.33 × 10⁻⁶ = n (470 × 10⁻⁹)

               n = 7

hence,

The number of spots will be:

→ N = 2n + 1

By putting the values,

      = 2 × 7 + 1

      = 14 + 1

      = 15

Thus the above answer is appropriate.  

Find out more information about wavelength here:

https://brainly.com/question/10750459

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