29 A pattern of interference fringes is produced using a red laser, a double slit and a screen. The screen is 3.5m from the double slit. The light from the laser has a wavelength of 640 nm.
The pattern of fringes is shown.
bright
fringe
1
not to
scale
72 mm
What is the separation of the slits?
A 1.2 x 10 m B 1.6 x 10 m
C 3.1 x 10 m
D 3.3 x 10 m
(очC