Question 111: Ray Optics

Question

A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is –3, then the magnitude of the radius of curvature of the mirror is :

Accepted Answer

$$\begin{aligned}
& \mathrm{m}=-3=-\frac{\mathrm{v}}{\mathrm{u}} 	ext { and } \mathrm{v}-\mathrm{u}=20 \mathrm{~cm} \
& \mathrm{f}=\frac{\mathrm{vu}}{\mathrm{v}+\mathrm{u}}=\frac{(-30)(-10)}{-30-10} \
& 	herefore \mathrm{R}=+15
\end{aligned}$$

Answer

3.75 cm

Answer

15 cm

Answer

7.5 cm

Answer

30 cm

Ray Optics

A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is –3, then the magnitude of the radius of curvature of the mirror is :

Choose the correct answer: