The Perfect Bounce
Reflection — light's unbreakable rule
What this lesson covers
Why it matters
Light plays a perfect game of carrom: every bounce off a mirror leaves at exactly the angle it arrived. No exceptions, ever — and you can aim with it.
Predict first
A ray hits a mirror at 30° from the normal. It bounces off at…
Angle in = angle out, both measured from the normal (the perpendicular). That's the law of reflection — light's oldest promise.
- 30° on the other side of the normal — correct
- 60°
- whatever angle it likes
What you do
Tilt the mirror and steer the reflected beam onto the sensor — the law does the aiming.
Check yourself
Angles of incidence and reflection are measured from…
Always from the normal — the examiner's favourite trap.
You can read this page from anywhere in the room because paper reflects light…
Rough surfaces scatter — no image forms, but everyone gets some light.
The speed of light is about…
3 × 10⁸ m/s. Light could circle the Earth about 7 times in one second — sound would need over 33 hours for one lap.
- the normal (the perpendicular to the mirror) — correct
- the mirror surface
- the floor
- irregularly, scattering it in all directions — correct
- like a mirror
- not at all
- 3,00,000 km every SECOND — nothing in the universe is faster — correct
- 300 km per hour
- the same as the speed of sound