# Wave Reflection Question

1. Feb 12, 2008

### _Mayday_

I am having trouble understanding this idea, I will quote what I have read and then post an image. This is not a homework question if anyone asks, it is an extension of what I am doing at school, but I would like to do some work through my week off. :tongue:

"Waves that are incident on solid surfaces obey the law of reflection. The angle between the direction of travel of the incident wave energy and the normal to the surface is equal to the angle between the direction of travel of the reflected energy and the normal."

http://img201.imageshack.us/img201/6739/wavesol6.png [Broken]

Question

a) What is the "incident"? I have looked it up but everywhere I look it is written in a way I do not understand, could someone please dum it down a bit :shy:

b) On the diagram I do not know what is happening? Like where is the wave coming from and what is the normal and reflected energy?

Any help would be great

Last edited by a moderator: May 3, 2017
2. Feb 12, 2008

### Hootenanny

Staff Emeritus
The "incident ray" simply means the incoming ray as opposed to the reflected ray. Imagine shining a laser onto a mirror, the part of the beam between your laser and the mirror is the incident beam since the light is traveling towards the mirror; once the beam has "touched" the mirror it becomes the reflected beam. I hope that clears it up.
Following on from my previous comment, you should know be able to determine where the light is coming from. The normal is just a "theoretical" line that is drawn normal (or perpendicular/orthogonal) to the mirror at the point where the beam "hits" the mirror. The reason it's there is the angles of incidence and reflection are measure from the normal line.

3. Feb 12, 2008

### Danger

As far as I know, 'incident' simply means that it hits the thing. At least, that's what it means in 'literary' English. As in "The sunlight incident upon the meadow scared the hell out of the vampires who were sleeping in the dandilions."
The picture seems to indicate a basic reflection wherein the angle at which something exits a target is equal but opposite to that with which it 'incidented'.

edit: Oops! Hi, Hoot. You sneaked in whilst I was composing.
Love your avatar, by the bye. Hugh Laurie rules!

4. Feb 12, 2008

### Hootenanny

Staff Emeritus
Hi Danger! That's right Danger I've been behind you all day .... Hugh Laurie is awesome, especially in House.

5. Feb 12, 2008

### _Mayday_

It's amazing how much more sense that makes than how the book put it. :tongue: Thanks again Hoot!

Thanks Danger, yeh I have to agree with you on that one the avatar is pretty sweet. I think I may become a contributer just to have a cool avatar and this site is like a second teacher :!!)

6. Feb 12, 2008

### Danger

I'm more of an evil influence than a teacher myself, but everyone here is very proud when someone benefits from the site. Having an avatar and signature are nice perks, but not necessities. The real reason for becoming a contributor is to help keep the site going and growing and helping more people. I'd keep paying even if I got banned.

7. Feb 12, 2008

### Hootenanny

Staff Emeritus
A pleasure as always Mayday