Question

an object of 5.0 cm size is placed at a distance of 20.0 cm from a converging mirror of focal length 15.0 cm at what distance from the mirror should a screen be placed to get a sharp image also calculate the size of the image

Answer 1

Heya user,

Object distance = u = - 20cm
Focal length = f = - 15cm

We have to find the Place at which sharp image of object is made---> basically, we have to find image distance or 'v'

.'. By formula, 

-----> 1/f = 1/u + 1/v
===> 1/(-15) = 1/(-20) + 1/v
===> v = [ 20 * 15 ] / [ 15 - 20 ] = 300 / -5 = - 60cm

Hence, The screen needs to be placed at 60 cm before the Converging mirror... --> [ to enjoy your movie in HD :-) Hehe ]

Now, -v/u = image size / object size

.'. Image size = 60cm / 20cm * 5cm = 15cm

.'. The Image is going to be 15cm large....... :-) [ Really Theatrical ]

Answer 2

Hey here is your answer!! ❤️❤️

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U = -20cm

V = ?

F = -15 cm

H = 5cm

By mirror formula,

1/v + 1/u = 1/f

1/v + 1/-20 = 1/-15

1/ v - 1/20 = 1/-15

1/v = 1/-15 + 1/20

1/v = (-4 + 3)/60

1/v = 1/60

Therefore, V = 60cm

Now again,

m= -v/u = h¹/h

= -60/-20 = 5/ h

= 3 = 5/h

= 3×5 = h

= 15cm

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HOPE ITS HELPS YOU.....