Light Emitting Diodes (LEDs) are semiconductor devices that emit light at specific wavelengths without emitting at any other wavelengths. LEDs can be used to create lasers that are very compact since they are a solid state device. A pair of narrow, parallel slits separated by 0.267 mm are illuminated by the green LED laser (λ = 546.1 nm). The interference pattern is observed on a screen 1.35 m from the plane of the parallel slits.

What is the distance between the first and second dark fringes?

Δx = 2.76 x 10⁻³ m = 2.76 mm

Explanation:

The distance between any two consecutive dark or consecutive bright fringes is given by:

Δx = λL/d

where,

Δx = distance between first and second dark fringe = ?

λ = wavelength of light = 546.1 nm = 546.1 x 10⁻⁹ m

L = distance between slits = 1.35 m

d = slit separation = 0.267 mm = 2.67 x 10⁻⁴ m

Therefore,

Δx = (546.1 x 10⁻⁹ m)(1.35 m)/(2.67 x 10⁻⁴ m)

Δx = 2.76 x 10⁻³ m = 2.76 mm

the answer would be a

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