Question

Find the size height and the position of Image formed by a concave mirror when a object of size 1 cm is placed at a distance 10 cm. Given focal length of mirror is 10cm

Answer 1

GivEn

• Object size is 1cm
• Object is placed 10cm at a distance from mirror
• focal length is 10cm

To FinD

• The size and the position of the object

SoluTion

Given ,

Object distance, u = -10cm

Focal length , f = -10cm (Since Concave mirror)

Therefore , from mirror formula we have :

$\dashrightarrow\tt \dfrac{1}{v} + \dfrac{1}{u} = \dfrac{1}{f} \\ \\ \tt \implies \dfrac{1}{v} = \dfrac{1}{f} - \dfrac{1}{u} \\ \\ \tt\implies \dfrac{1}{v} = \dfrac{1}{ - 10} - \dfrac{1}{ - 10} \\ \\ \implies \tt \dfrac{1}{v} = - \dfrac{1}{10} + \dfrac{1}{10} \\ \\ \implies \tt \dfrac{1}{v} = 0 \\ \\ \tt \implies v = \dfrac{1}{0} \\ \\ \tt \implies v = \infty$

Thus , the image will form at infinity.

Now by the formula of magnification ,

$\implies\tt \dfrac{h_2}{h_1} = - \dfrac{ v}{u} \\ \\ \implies \tt h_2 = - \frac{ \infty }{ - 10} \times 1cm \\ \\ \implies \tt h_2 = \infty$

Thus the size of the image will form huge that it can't be defined