A diffraction grating produces its first-order bright spot at an angle of 40°.If you want to reduce this angle to 20° for the same wavelength of light,you must double the line density of the grating.

Question

Quizplus · Accepted Answer

The angle of diffraction is given by the equation sinθ = nλ/d, where n is the order of the maxima, λ is the wavelength of light, and d is the spacing between the lines on the grating. If the first-order bright spot occurs at 40° for a certain wavelength of light and line density, doubling the line density (i.e., halving the spacing d) would increase the angle of diffraction, not decrease it. Therefore, statement B is correct. To reduce the angle of diffraction, one would need to change the wavelength of light or use a grating with wider line spacing.

A Diffraction Grating Produces Its First-Order Bright Spot at an Angle