The plane containing the incident ray and normal is called :

1. plane of reflection
2. normal plane
3. plane of incidence
4. none of the above

Regular reflection occurs when a beam of light falls on a ……………

1. smooth surface
2. polished surface
3. rough surface
4. Both (a) and (b)

According to the law of reflection:

1. $\dfrac{i}{r}$ = Constant

2. $\dfrac{\text {sin i}}{\text {sin r}}$ = Constant

3. i + r = Constant

4. i = r

For a ray incident normally on a plane mirror, the angle of incidence is :

1. 90°
2. 45°
3. 30°
4. 0°