Question

State the condition for each of the following:
(i) A lens has both its focal length equal.
(ii) Two thin lenses when placed in contact has zero power.​

Answer 1

Explanation:

1. Focal point is the point where parallel rays meet after passing through the lens. If the medium on both sides is same, the focal point will be the same and hence, same focal lengths.

Answer 2

Equivalent power, Peq=P

1

+P

2

−P

1

P

2

d

Given, 10=P

1

+P

2

Putting values, 6=P

1

+P

2

−0.25P

1

P

2

4

1

P

1

P

2

=4

P

1

P

2

=16

10P

2

=P

2

2

+16

P

2

2

−10P

2

+16=0

P

2

=2D,P

1

=8D

MARK ME AS BRAINLY