Question

If an object is placed at a distance of 20 cm in front of a concave mirror of focal length 5 cm, find the

image distance.
​

Answer 1

Answer:

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12th

Physics

Ray Optics and Optical Instruments

Combination of Lenses

An object 5 cm is placed ...

PHYSICS

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Asked on December 20, 2019 by

Priyadharshini Devnal

An object 5cm is placed at a distance of 20cm in front of a convex mirror of radius of curvature 30cm. Find the position of the image, its nature and size.

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ANSWER

Formula:

v

1

+

u

1

=

f

1

Given,

v

1

+

(−20)

1

=

15

1

v

1

=

60

7

⇒v=

7

60

v=8.57≈8.6cm

The image is formed behind the mirror at a distance of 8.6 cm

m=

h

1

h

2

=−

u

v

→

5

h

2

=−

20

8.57

∴h

2

=2.175 cm

Thus the image is 2.175 cm high, virtual and erect.

Hence, this is the answer.

Answer 2

The answer is 2.175.......

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