Question

an object is placed at dist 25cm in front of concave mirror and image has magnification of -2 .find focal length

Answer 1

Given,

Object distance, u=25cm

Focal length, f=20cm

From mirror formula

f

1

​

=

v

1

​

+

u

1

​

−20

1

​

=

v

1

​

−

25

1

​

⇒

v

1

​

=−

20

1

​

+

25

1

​

v=100cm

The image will be real, inverted magnified

Step-by-step explanation:

Given,

Object distance, u=25cm

Focal length, f=20cm

From mirror formula

f

1

​

=

v

1

​

+

u

1

​

−20

1

​

=

v

1

​

−

25

1

​

⇒

v

1

​

=−

20

1

​

+

25

1

​

v=100cm

The image will be real, inverted magnified