Question

An object 4 cm high is placed 40 cm in from of a concave mirror of focal length 20 cm. find

the distance from the mirror, at which a screen be placed to obtain a sharp image.

(v= - 40cm)​

Answer 1

Explanation:

HEYY!! MATE HERE IS YOU'RE ANSWER

ho(height of object) = 4 cm

u = -40 cm

f (focal length) = -20cm

hi (height of image) =?

v=?

By mirror formula,

1/f = 1/v-1/u

1/-20 = 1/v - 1/-40

1/v =1/-20 + 1/-40

1/v = -2+1/40

1/v = -1/40

v = -40 cm

Nature of image = real and inverted.

Now m=hi/ho=-v/u

hi/4 = - (-40)/-40

hi/4=40/-40

hi/4 = -1

hi = - 1(4)

hi = -4 cm

I hope it will help u buddy.

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4.8

ho(height of object) = 4 cm

u = -40 cm

f (focal length) = -20cm

hi (height of image) =?

v=?

By mirror formula,

1/f = 1/v-1/u

1/-20 = 1/v - 1/-40

1/v =1/-20 + 1/-40

1/v = -2+1/40

1/v = -1/40

v = -40 cm

Nature of image = real and inverted.

Now m=hi/ho=-v/u

hi/4 = - (-40)/-40

hi/4=40/-40

hi/4 = -1

hi = - 1(4)

hi = -4 cm

I hope it will help u buddy.

Pls mark it as brainliest ans brother.

Answer 2

ho(height of object) = 4 cm

u = -40 cm

f (focal length) = -20cm

hi (height of image) =?

v=?

By mirror formula,

1/f = 1/v-1/u

1/-20 = 1/v - 1/-40

1/v =1/-20 + 1/-40

1/v = -2+1/40

1/v = -1/40

v = -40 cm

Nature of image = real and inverted.

Now m=hi/ho=-v/u

hi/4 = - (-40)/-40

hi/4=40/-40

hi/4 = -1

hi = - 1(4)

hi = -4 cm

I hope it will help u buddy.

Pls mark it as brainliest ans brother.