Question

what is the angle of incidence

Answer 1

I picture is worth 1000 words so look at this and post any follow-up questions you may still have:

Answer 2

best response but i need the answer theoretically plz define the ans with some examples and give me detail of my question. thanks for the reply.

Answer 3

If you look at the picture you can see the ball coming in from the left hand side and striking the wall. The angle of incidence is the angle in which the object strikes a surface with respect to the line that is drawn perpendicular to the surface (the normal).

In the image, the angle of incidence will equal the angle of reflection.

You can read more about this here:
http://en.wikipedia.org/wiki/Angle_of_incidence