How many grating grooves are needed to resolve two spectral lines at λ = 351 nm separated by 0.59 nm in order m = 4?
A)149 grooves
B)595 grooves
C)0 grooves
D)297 grooves

Question

Quizplus · Accepted Answer

The resolving power of a grating is given by R = λ/Δλ, where λ is the wavelength of light and Δλ is the wavelength difference between the two lines that can be resolved. In this case, λ = 351 nm and Δλ = 0.59 nm, so R = 351 nm/0.59 nm = 595. The number of grating grooves needed to achieve this resolving power is given by N = mR, where m is the order of the diffraction pattern. In this case, m = 4, so N = 4 * 595 = 2380.

How Many Grating Grooves Are Needed to Resolve Two Spectral