The magnification of a convex mirror is 0.7 CM when an object is kept at distance of 30 cm from its find the focal length

Asked by ajajaysanja | 23rd Oct, 2019, 02:22: PM

Expert Answer:

Magnification m = -v/u  = 0.7
 
where v is mirror to image distance and u is mirror to object distance .
 
we are given u = -30 cm ( Cartesian sign convention is applied)
 
hence , v = 0.7×30 = 21 cm
 
we have mirror eqn., (1/v) + (1/u) = 1/f, where f is focal length
 
1/f = (1/21) - (1/30) = 1/70   or focal length f = 70 cm

Answered by Thiyagarajan K | 23rd Oct, 2019, 06:10: PM