Q1.
Do you remember learning earlier that the light travels along a straight line?
Answer
Yes. In a single uniform medium light travels in straight lines, and that is exactly why we are allowed to draw it as straight lines with arrows — as rays.
The evidence is all around us:
- A shadow has the sharp outline of the object, and a bigger object makes a bigger shadow — which is what straight-line travel predicts.
- Light from a torch passing through a slit shows up as a straight streak on the paper, never a curved one.
- You cannot see round a corner, and a beam through a bent pipe does not come out at the far end.
Why the ray model is so useful here: once we accept that light travels in straight lines, a whole diagram can be drawn with a ruler. The path of the light before the mirror is one straight line, the path after the mirror is another, and the only thing left to work out is the angle between them — which is what the laws of reflection give us.