Question

an object of a centimetre in size is placed at a distance of 40 cm from a concave mirror of focal length 15cm distance from the mirror should a screen be placed to get this is also calculate size of the image​

Answer 1

Answer:

the answer is 24 cm and 0.6 cm

Explanation:

given, v=?, u= 40 cm, f= 15 cm

formula: 1/f = 1/v + 1/u

=> 1/15 = 1/v + 1/40

=> 1/15 = 40+v /40v

By cross multiplication ,we get,

40v = 15(40+v)

=> 40v = 600 + 15v

=> 40v - 15v = 600

=> 25v = 600

=> v = 600/25

=> v =24

therefore, the image distance is 24 cm.

Now, magnification(m) = v/u

              =24/40

              =3/5

Also, m= Image size/Object size

=> 3/5 = I/1

=>5I = 3

=> I = 3/5

=> I = 0.6

therefore size of image is 0.6 cm.

(note: since it is concave lens values of u, v, and f all are positive.)