In a certain Young's double-slit experiment, a diffraction pattern is formed on a distant screen, as the drawing shows. The angle that locates a given bright fringe is small, so that the approximation sin θ ‰ˆ θ is valid. Assuming that θ remains small, by what factor does it change if the wavelength λ is doubled and the slit separation d is doubled?
(a) The angle does not change.
(b) The angle increases by a factor of 2.
(c) The angle increases by a factor of 4.
(d) The angle decreases by a factor of 2.
(e) The angle decreases by a factor of 4.

Bright fringe Double slit