(a) (i) State laws of reflection of light. (ii) An object of height 5⋅0 cm is placed at 15 cm in front of a concave mirror of focal length 10 cm. At…

(a) (i)

The angle of incidence is equal to the angle of reflection.

The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane.

(ii) \(\displaystyle \mathrm{u}=-15 \mathrm{~cm}, \mathrm{f}=-10 \mathrm{~cm}\) (concave mirror) \[h=5.0 \mathrm{~cm} \] Mirror formula \(\displaystyle \frac{1}{f}=\frac{1}{v}+\frac{1}{u}\) \[\frac{1}{v}=\frac{-1}{10 \mathrm{~cm}}+\frac{1}{15 \mathrm{~cm}}=\frac{-1}{30 c m} \] or \(\displaystyle \mathrm{v}=-30 \mathrm{~cm}\). The screen must be placed at a distance of $\displaystyle 30$ cm from the mirror in front of it

\(\displaystyle (m)=\frac{h^{\prime}}{h}=-\frac{v}{u}\) \(\displaystyle h^{\prime}=\frac{-v}{u} \times h=-\frac{-30 c m}{-15 c m} \times 5 c m=-10 \mathrm{~cm}\)

-The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in the same plane.

The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media. / \[\frac{\sin i}{\sin r}=\text { constant } \]

The emergent ray is parallel to the incident ray.

Labelling of lateral displacement