Question

when an object is placed at a distance of 50cm from a concave spherical mirror, the magnification produced is, -1/2 . Where should the object be placed to get a magnification of -1/5

Answer 1

Answer:

Explanation

Since by the lens formula;1f=1do+1di(1)

where do=50cm is the distance of the object from the concave mirror (2)

and fis the focal length of the mirror so that;

f=CV2=20cm2

f=10cm(3)

Rearranging (1);

1di=1f−1do(4)

Putting (2) and (3) in (4)

1di=110−150

1di=450

di=504

di=12.5cm to the left of the mirror in the image above.

Magnification, M is given by;

M=hiho=dido

where hi and ho are image and object heights respectively. So

M=12.5cm50cm

M=0.25

The image height is a quarter the height of the object

Answer 2

we should place the object to get a magnification of-1/5 is at 25 cm