How wide must a narrow slit be if the first diffraction minimum occurs at ±12° with laser light of 633 nm?
A)3.0 × 10−6 m
B)3.0 × 10−5 m
C)6.1 × 10−6 m
D)6 .1× 10−5 m
E)1.5 × 10−6 m

Question

Quizplus · Accepted Answer

The correct answer is A.The first diffraction minimum occurs when the path length difference between the two waves is equal to half a wavelength. The path length difference is equal to the width of the slit times the sine of the angle of diffraction. So, the width of the slit is equal to half a wavelength divided by the sine of the angle of diffraction.In this case, the wavelength of the laser light is 633 nm and the angle of diffraction is 12 degrees. So, the width of the slit is:w = (633 nm) / (2 * sin(12 degrees)) = 3.0 x 10^-6 m

How Wide Must a Narrow Slit Be If the First