Question

An object is placed at the focus of a concave mirror which has a focal length of
4 cm. At what distance is the image of that object formed? Draw the ray diagram. ​

Answer 1

Answer:

h1= 2cm, u = -9cm, f = -4cm

We know that

1/v + 1/u = 1/f

1/v = 1/f – 1/u = 1/(-4) – 1/(-9)

= - (1/4) + 1/9 = (-9 + 4)/36 = - (5/36)

V = - 7.2 cm

The image is formed at a distance 7.2 cm in front of the mirror

Again, m = - (v/u) = - (-7.2)/-9 = -0.8

m = h2/h1 ⇒ -0.8 = h2/2 ⇒ h2 = -1.6 cm

So, image is 1.6 cm in size, real and inverted.