# Huygen's principle on waves.

1. Oct 25, 2016

### Aliasa

1. The problem statement, all variables and given/known data

2. Relevant equations
N/A

3. The attempt at a solution

Okay, it is not an assignment question. I am just looking for an explanation regarding something I read. Why is the diagonal distance travel time(^-1) equal to $$(n_2 - n_1){(\frac{1}{c_1} + \frac{1}{c_2})}$$ ?

2. Oct 25, 2016

### BvU

3. Oct 25, 2016

### olivermsun

Did you try to equate the two paths? If so, where did you get stuck?