Question

The image of a candle flame placed at a distance of 30 cm from a mirror is formed on a screen placed in front of mirror at a distance of 60 cm from its pole. What is the nature of the mirror. Find its focal length. If the height of flame is 2.4 cm , find te height of image.
1) what is the nature of the mirror
2) Find its focal length
3) If the height of the flame is 2.4cm find the height of its image

Answer 1

Hello guys Namaste,

1/-30+1/-60=1/f

=>(-1-2)/60=1/f

=>-3/60=1/f

=>-20=f

.focal length = -20 cm

m=-v/u=h'/h

-(-60)/-30=h'/2.4

h'=-4.8

therefore, image is inverted , real , magnified, formed beyond c

Answer 2

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✏️ Answer:-

★ Nature of the mirror = Concave.

★ Focal length = - 20 cm.

★ Height of the image formed = - 4.8 cm. (inverted).

✏️ Explanation:-

★ From the above mentioned scenario, it's clear that the nature of the mirror here is Concave.

★ Given –

• h = + 2.4 cm,

• u = - 30 cm,

• v = - 60 cm,

★ To find –

• f = ?

★ Rationale –

• From the mirror formula, we have,

1/f = 1/v + 1/u

Now,

On plugging in the values from the question, we get,

1/f = 1/-60 + 1/-30

∴ f = -20 cm.

We know that,

m = h'/h = -v/u

⇒h' = - h × v/u

⇒h' = - 2.4 cm × -60/-30 cm

∴ h' = - 4.8 cm.

[ Note:- The -ve sign of h' (image size) indicates that the image formed is inverted. ]

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I hope this helps! :)