PhysicsChapter 4: Diffraction and Interference
Diffraction Grating Equation and Spectroscopy
For a diffraction grating, principal maxima occur when the path difference between waves from adjacent slits is an integer number of wavelen
Definition
For a diffraction grating, principal maxima occur when the path difference between waves from adjacent slits is an integer number of wavelengths.
Central Maximum
For slit spacing: d and diffraction angle: θ path difference between adjacent slit waves is: d sinθ For constructive interference: d sinθ=nλ where: `n = 0, ±1, ±2...` is diffraction order. For: `n=0` **θ=0**
First Order
`n=1` **d sinθ=λ**
Maximum Possible Order
Because: **sinθ≤1 we require: nλ≤d**
Spectroscopy
Different wavelengths satisfy the grating equation at different angles. Therefore white or mixed light can be separated into its component wavelengths. Diffraction gratings are consequently useful for: wavelength measurement, spectral analysis, identifying emission/absorption features. The chapter's current resources explicitly highlight grating applications in spectroscopy and wavelength measurement. ([YouTube][3])
Formula / Key Relation
**d sinθ=nλ**
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Diffraction Grating Equation and Spectroscopy
Sticky Notes · Quick Revision
GRATING
- `d sinθ=nλ`
- Different λ → different θ
- → spectrum
60-second revision
- A diffraction grating separates wavelengths because each wavelength has a different diffraction angle.
Did you understand this topic?
Your answer is saved with your learning record. It does not mark the topic as mastered.