Physics - Geometrical Optics Question with Solution | TestHub

Bylens formula $$\begin{array}{l}\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\\ \frac{1}{v}-\frac{1}{(-20)}=\frac{10}{3}\\ \frac{1}{v}=\frac{10}{3}-\frac{1}{20}\\ \frac{1}{v}=\frac{197}{60};v=\frac{60}{197}\end{array}$$ Magnification of lens (m) is given by $$\mathrm{m}=\left(\frac{\mathrm{v}}{\mathrm{u}}\right)=\frac{\left(\frac{60}{197}\right)}{20}$$ velocity of image wrt. to lens is given by $${\mathrm{v}}_{\mathrm{J}/\mathrm{L}}={\mathrm{m}}^2{\mathrm{v}}_{\mathrm{O}/\mathrm{L}}$$ direction of velocity of image is same as that of object $$\begin{array}{l}{\mathrm{v}}_{\mathrm{O}/\mathrm{L}}=5\mathrm{m}/\mathrm{s}\\ {\mathrm{v}}_{\mathrm{I}/\mathrm{L}}={\left(\frac{60\times 1}{197\times 20}\right)}^2\end{array}$$ $=1.16\times 10^{-3}\mathrm{m}/\mathrm{s}$ towards the lens