# Homework Help: Phase reversal of reflections

1. Jan 6, 2005

### yaffle

I know that waves on a string are inverted on reflection from a hard surface. How about light waves and sound waves?

2. Jan 6, 2005

### dextercioby

I don't unserstand what u could possbly mean by 'inverted',but i can tell you that sound and light waves get a phase shift by $\pi$ radians on each reflection.

Daniel.

3. Jan 6, 2005

### Staff: Mentor

Light reflecting from a material of higher index of refraction will get phase shifted by $\pi$ radians (thus "inverted"), but light reflecting from a material of lower index of refraction will not get phase shifted.

Sound waves reflecting from a hard surface will get phase shifted by $\pi$ radians.

4. Jan 7, 2005

### yaffle

Thanks:
Sorry I thought everyone would be familiar with the concept of a phase shift of pi radians as being "inverted"
however,
I guess this means that light reflected from a mirror or any object eg. an apple is phase shifted by pi radians?

5. Jan 7, 2005

Exactly! :-)