Before changinh direction?

No the wave just doesn't stop. Like light, the waves gets reflected and bounces back, not necessarily in the same direction, but if you know about the angles of incidence and reflected angle, they should be equal.

Unless you have something else involved which might change that. But let's not get into there.

when light hitsa a mirror...
analysed in 2 ways...
1. photon theory.
the small packets of light, coming in from a source headed for da mirror.. hit da first layer of molecules of da mirror... as da mirror can be assumed to be made of sheets of molecules... one after anoder..
now imagine it, da photons.. bombard a molecule,, and give it its complete energy .
at this point what actually existed as a photon is now no longer existing.
its like da photon was energy , having collided with 'molecule' and given away its energy dere is no photon now, but what we do have is a molecule of da mirror having more energy den it is usually supposed to have or what we may call the 'excited state' and remember da maths, it is now having just da same amount of additional energy that da photon carried to it,
no to relieve itself of this excited state... da molecule fires anoder round of energy randomly... to come to its normal state... now this random ball of energy 'new photon' can go anywhere deeper into da mirror layers, and keep repeating this collision phenomenon until it is released in da right direction that is da way out.. out of da sheets of mirror molecules...
now all this is happening and billions of photons are colliding with billions of molecules of mirror... now if u wonder da time lag, den da answer is simply da high value of speed of light which makes it impossible for us to see da events happening at this micro level to be processed.



2. the wave nature.
simply studying snell's law... might help.

Thanks