Key relationship
v=c/n; λ₁=λvac/n₁; λ₂=λvac/n₂; frequency unchanged; n₁sin i=n₂sin r.
Physics · Class 12
Huygens wavefront refraction
Every point on a wavefront acts as a source of secondary wavelets. A slower wave advances less far during the same time, tilting the new wavefront. The frequency remains fixed at the boundary.
Open the interactive experiment →Huygens wavefront refraction
அலைமுகத்தின் ஒவ்வொரு புள்ளியும் துணை அலைகளை உருவாக்கும். ஊடக எல்லையில் அதிர்வெண் மாறாது; வேகமும் அலைநீளமும் மாறும்.
Key notes, relationships and model limits
Remember
Every point on a wavefront acts as a source of secondary wavelets. A slower wave advances less far during the same time, tilting the new wavefront. The frequency remains fixed at the boundary.
Common trap
Wavefronts are perpendicular to rays, not the same lines.
Model limits
This panel illustrates wavefront refraction and its TIR branch. A separate Huygens construction for reflection is outside this panel.
What you will learn
Connect wavefront construction to refraction.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
A600 nm vacuum wavelength becomes400 nm in index1.5.
Why this matters
The model connects huygens wavefront refraction with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
Light enters index1.5 from air. Which remains unchanged?
- Wavelength
- Frequency
- Speed
Read the explanation
The source fixes frequency; speed and wavelength both decrease by1.5.
Course connection: Class XII Chapter 10. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.