Question

Sunlight of intensity 0.3 kWm-2 is incident normally on a thin convex lens of focal length 20 cm. Ignore the
energy loss of light due to the lens and assume that the lens aperture size is much smaller than its focal
length. The average intensity of light, in kWm-?, at a distance 22 cm from the lens on the other side is​

Answer 1

Answer:

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Explanation:

Correct option is

A

130

R

r

=

20

2

=

10

1

∴ Ratio of area =(

R

r

)

2

=

100

1

Let energy incident on lense be E.

∴ Given

A

E

=1.3

To calculate: final

a

E

E=a×1.30

Also

A

a

=

100

1

∴ Average intensity of light at 22cm=

a

E

=

a

A×1.3

=100×1.3=130kW/m

2

Answer 2

Answer:

here is ur answer hope u have been understood

Explanation: