Question

an object 4cm high is placed 40.0cm in front of a concave mirror of focal length 20cm.find the distance from the mirror,at which a screen is placed in order to obtain a sharp image .also find the size and nature of the image formed.​

Answer 1

Given:

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

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Answer 2

Answer:

Step-by-step explanation:

Given: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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