Question

Concentrated image of the sun can be foccused at 50cm away from a mirror.What is the focal length of the mirror?​

Answer 1

Answer:

Answer

Correct option is

A

75cm

Given,

Focal length, f=50cm

Magnification, m=2

m=

u

v

=2

v=2u

From mirror formula,

f

1

=

v

1

+

u

1

f

1

=

2u

1

+

u

1

u=

2

3f

=

2

3×50

=75 cm

Object Is placed at 75cm from the mirror.

Answer 2

Answer:

Given,

Focal length, f=50cm

Magnification, m=2

m=

u

v

=2

v=2u

From mirror formula,

f

1

=

v

1

+

u

1

f

1

=

2u

1

+

u

1

u=

2

3f

=

2

3×50

=75 cm

Object Is placed at 75cm from the mirror.