Question

The interference pattern of a He-Ne laser light (λ=632.9nm) passing through two slits 0.031 mm apart is projected on a screen 10.0 m away. Determine the distance between the adjacent bright fringes.

a. 0.632 mm
b. 1.26 mm
c. 1.26 cm
d. 6.32 cm

Answer 1

Using the two-slit interference formula and substituting the given values, the distance between the adjacent bright fringes is approximately 2.0435 mm. None of the answer choices provided (0.632 mm, 1.26 mm, 1.26 cm, 6.32 cm) match this calculated result.

Step-by-step explanation:

To determine the distance between adjacent bright fringes in the interference pattern of a He-Ne laser light, we use the formula for two-slit interference:

1. First, identify the given values: wavelength (λ) is 632.9 nm, slit separation (d) is 0.031 mm, and the distance to the screen (L) is 10.0 m.
2. Convert the units to meters: 632.9 nm = 632.9 x 10-9 m, 0.031 mm = 0.031 x 10-3 m.
3. The formula for the distance (Δy) between the bright fringes is Δy = (λ×L)/d.
4. Substitute the values into the formula: Δy = (632.9 x 10-9 m -3 m) = 2.0435 x 10-3 m = 2.0435 mm.

The distance between adjacent bright fringes is approximately 2.0435 mm, which can be rounded to 2.04 mm, but this option is not given. Please check the set options again, as none of the provided choices matches the result from the calculation.