Double-slit interference: In a double slit experiment, the slit separation is constructed to be exactly 4 times the wavelength of the light passing through the slits. At what angles from the center of the pattern will the third bright fringes on both sides of the central fringe occur?
A) ±48.6°
B) ±75.0°
C) ±67.5°
D) ±36.9°
E) ±43.0°

Question

Quizplus · Accepted Answer

The angle for bright fringes in a double-slit experiment is given by the formula $d \sin \theta = m \lambda$, where $d$ is the slit separation, $\theta$ is the angle, $m$ is the fringe order, and $\lambda$ is the wavelength. For the third bright fringe ($m = 3$) and $d = 4\lambda$, we have $4\lambda \sin \theta = 3\lambda$, leading to $\sin \theta = \frac{3}{4}$. Solving for $\theta$, we get $\theta = \sin^{-1}(0.75) \approx 48.6^\circ$.

Double-Slit Interference: in a Double Slit Experiment, the Slit Separation