Question

A bright object 50mm high stands on the axis of a concave mirror of focal length 100mm at a distance of 300mm from the concave mirror. How big will the image be ?​

Answer 1

Explanation:

Distance of the object from the mirror 'u' =300mm

Height of the object 'ho'= 50mm

focal length of the mirror 'f' =-100mm

we have to find the distance of the image'v' and the height of the image 'hi''.

'1/f=1/v+1/u'

'1/-100 =1/v+1/-300'

'-1/100 =1/v-1/-300'

'1/v=1/300-1 /100'

'1/v=1/300-1/100'

'1/v=(-2)/300'

v=-150cm

Thus,the image will be at distance of 150mm in front of the mirror. Now, using the magnification formula we get

m= hi/ho=_v/u

hi/50=_150/300 =_1/2

hi=_50/2=_25mm

Thus, the size of the image will be the 25mm

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