Question

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal
length 18 cm. At what distance from the mirror should a screen be placed, so that
a sharp focussed image can be obtained? Find the size and the nature of the image.

NCERT Class X
Science - Science

Chapter_Light – Reflection and
Refraction

Answer 1

Given
 Size of the object [o] = +7cm
  F = -18cm
  U= -27cm
 V = ?
 1/f = 1/v+1/u
 1/-18cm = 1/v-1/27
  1/v= -1/54 v = -54cm
Since Vis – ve screen should be placed at 54cm in front of the mirror.
Size of the image : m= I/O= -v/u I/7=-[54/27] I= -14cm
Nature of the image : image is real , inverted and magnified. 

Answer 2

HEY MATE HERE IS UR ANSWER:-


Object height (h) =7cm
Object distance (u) =-27cm
Focal lenght of the concave mirror (f) =-18cm

Using mirror Formula, 1/f=1/v+1/u
we get, 1/v=1/f-1/u
1/v=(1/-18)-(1/-27)
=-1/18+1/27
= -3+2/54

1/v =-1/54

v=-54cm

by using m= h/h'= -v/u

7/h'=-(-54)/(-27)
h'=-7x(-54)/(-27)

h' =-14cm

Since h>h' the image is enlarged. As the value of h is negative, the image is inverter.

Since v is negative, the image formed is real.


PLEASE MARK AS BRAINLIEST
AND I HOPE THIS WILL HELP YOU...