Question

An object of height is 1.2 M is placed before a concave mirror of focal length 20cm so that a real image is formed at the distance of 60 cm from it find the position of an object what will be height of the imageformed

Answer 1

Reflecting telescopes use mirrors instead of lenses to collect light. Because mirrors have only one reflective surface, they are easier to construct than lenses, which are made from optical glass, and cannot have any occlusions because light must pass completely through them. In addition, mirrors have less spherical aberration, which is a scattering of light that occurs when lenses don't perfectly focus on a single point. Mirrors also reflect all wavelengths of light equally, whereas lenses bend light differently depending on its wavelength.

Answer 2

Answer:

u = 30 cm

$\display \text{h _i = 2.4 cm}$

Explanation:

We have given :

Focal length = 20 cm

Image distance =  60 cm

We have to find object distance .

We know :

1 / f = 1 / v + 1 / u

Since image formed is real :

f = - 20 cm and v = - 60 cm

1 / u = 1 - 3 / 60

u = - 30 cm

Hence object distance is 30 cm .

Also given object height = 1.2 cm

We know :

h_i / h_o = - v / u

h_i / 1.2 = - 60 / 20

h_i = - 2.4 cm

Hence image height is 2.4 cm .