JEE PYQ: Ray Optics Question 17
Question 17 - 2020 (03 Sep Shift 2)
When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm from the mirror. If the object is moved with a speed of 9 cms$^{-1}$, the speed (in cms$^{-1}$) with which image moves at that instant is __________.
Show Answer
Answer: (1)
Solution
Distance of object, $u = -30$ cm Distance of image, $v = 10$ cm Magnification, $m = \frac{-v}{u} = \frac{(-10)}{-30} = \frac{1}{3}$ Speed of image $= m^2 \times$ speed of object $= \frac{1}{9} \times 9 = 1$ cm s$^{-1}$
BETA
