Doubt by Maria
The focal length of a concave mirror is 30 cm. Find the position of the object in front of the mirror so that the image is three times the size of the object. consider two cases in which a) the image is real and the other in which b) the image is virtual
Answers
Answer by Divya Garg
Share your working. Where are you facing problem?
Answer by Maria
I couldn't understand the question.
Answer by Divya Garg
Since it is a concave mirror, focal length is -30 in the formula 1/v-1/u = 1/f. Now for a real image, the image will be inverted and for a virtual image it will not be. It is also given that u is negative because object is placed infront of the mirror. So take u to be negative everywhere.
For real image
m=-3 i.e. v/u = -3, v = 3u
1/3u+1/u=-1/30, u =-40 and v=-120
For virtual image
m=3 i.e. v/u = 3, v=-3u
-1/3u+1/u=-1/30, u=-20 and v=60
Answer by Maria
Thanks
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