Question

an object is placed at a distance of 4 cm in front of convex mirror whose focal length is 5 cm where the image is formed​

Answer 1

Answer

It is to be remembered that a convex mirror always forms the virtual, erect and diminished image.

Given: Object distance, u=−10cm Focal length, f=15cm

To find: Image distance, v

From mirror formula :

v

1

+

u

1

=

f

1

v

1

−

10

1

=

15

1

v

1

=

15

1

+

10

1

=

150

25

Hence image will be formed 6 cm beyond the mirror, i.e virtual magnification

m=

u

−v

=

−10

−6

=0.6

Answer 2

Explanation:

object Distance (u) = 4 cm (negative)

focal length of the lens (f) = 5 cm

we know, convex mirror always forms the virtual, upright and diminished. Also, object distance in the convex mirror os always negative where as image distance and focal length are positive.

Now, Applying the mirror's formula,

1/f = 1/v + 1/u

1/5 = 1/v +1

1/5 = (4-v) /4v

4v = 5(4-v)

4v = 20-5v

9v = 20

v = 20/9 = 2.222