Question

An object is placed at a distance of 30cm from a concave mirror. The magnification produced is 1/2. Find the image distance and focal length

Answer 1

Answer:

u= -30

m = 1/2

we know that m = -v/u

so v = 15

1/f = 1/v + 1/u 

 

f = 10

for m= 1/3 

-v/u = 1/3

v= -(1/3 * u)

1/f = 1/v + 1/u

1/10 = 3/-u + 1/u 

1/10 = -4 /u 

u = -40 

therefore for the magnification to be 1/3 the object must be placed 40 cm in front of the mirror

hope it helps !!