Join thousands of students who trust us to help them ace their exams!Watch the first video
Multiple Choice
A diffraction grating has If it is illuminated by a laser at how many bright spots will be observed on a screen placed behind the grating?
A
3
B
4
C
5
D
6
E
9
F
7
Verified step by step guidance
1
First, understand that a diffraction grating causes light to diffract at specific angles, creating bright spots known as maxima. The number of lines per millimeter on the grating is given as 500 lines/mm.
Convert the number of lines per millimeter to the grating spacing (d) in meters. The grating spacing is the inverse of the number of lines per meter. So, d = 1 / (500 * 1000) meters.
Use the diffraction grating formula to find the angles at which maxima occur: d * sin(θ) = m * λ, where m is the order of the maximum, λ is the wavelength of the light (532 nm), and θ is the angle of diffraction.
Determine the maximum order (m) for which the equation is valid. This occurs when sin(θ) is less than or equal to 1. Calculate the maximum m by rearranging the formula: m = d * sin(θ) / λ, and find the largest integer m that satisfies this condition.
Count the number of bright spots. Each order m corresponds to two bright spots (one on each side of the central maximum), except for the central maximum (m=0), which is counted once. Add these to find the total number of bright spots.