# Find the speed of the 2nd-order maxima on the screen

#### burgerkin

1. Homework Statement

A man holds a light that emits light of wavelength λ. The light beam passes though a pair of slits separated by a distance d, in a screen plate attached to the front of the light beam(double slits experiment). The beam then falls perpendicularly on a screen, getting an interference pattern on it. The man walks straight toward the screen at speed v. The central maximum on the screen is stationary. Find the speed of the 2nd-order maxima on the screen, where m can be very large. (Use variable or symbol )

2. Homework Equations

y=$$\lambda$$L m / d

3. The Attempt at a Solution

L changes with v, and y changes with v

so y = $$\lambda$$ v t m /d

then v 2nd order maximum (m=2) = y' = $$\lambda$$ v m /d
1. Homework Statement

2. Homework Equations

3. The Attempt at a Solution

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#### Redbelly98

Staff Emeritus
Homework Helper
3. The Attempt at a Solution

L changes with v, and y changes with v

so y = λ v t m /d

then v 2nd order maximum (m=2) = y' = λ v m /d
Your answer looks correct for small angles, even though L is not really equal to v·t.

I am puzzled by this statement:
Find the speed of the 2nd-order maxima on the screen, where m can be very large
For the 2nd-order maxima, m is 2, which is not a large number. Are you sure you typed this part of the question exactly as it was written in the problem statement?

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