Question

At what distance in front of a concave mirror of focal length 10cm, an object
be placed so that its real image of size five times that of the object is
obtained.​

Answer 1

Answer:

Physics

At what distance in front of a concave mirror of focal length 1010cm, an object be placed so that its real image of size five times that of the object obtain?

October 15, 2019Adlina Monika

SHARE

ANSWER

f=10f=10cm.

We know that, linear 

magnification

m=\displaystyle\frac{I}{O}m=OI

I=I= size of image

O=O= size of object

But, here the real image is 50 times of object.

I=50I=50

m=\displaystyle\frac{50}{0}=m=-5m=050=m=−5

By the definition of linear magnification

m=\displaystyle\frac{f-u}{f}m=ff−u

5=\displaystyle\frac{10-u}{10}5=1010−u

50=10-u50=10−u

u=40u=40

u=40u=40cm.

Object should be placed at 4040cm in front of convex mirror. Here -−ve sign represents that object is placed left side of the mirror.

Answer 2

Answer:

at 2 cm distance from the mirror