# Question on Optics, finding images of a pin using a concave mirror

A pin AB, 1cm long, is placed at an angle to the principal axis in front of a concave mirror, of focal length 5cm. Point B lies on the principal axis at a distance of 4 cm. Point A is such that the angle ABP is 60°, where P, the pole, is the point where the principal axis intersects the mirror.

a.) Find the positions of A' and B' of the needle's image.
b.) Determine the image's nature and magnification.

I have attempted to the solution but still i feel am in a sort of foolish mistakes...would be grateful if anyone can help me please. after going through the physics, i am sure and convinced that the image is an erected, magnified and virtual now...and obtained magnification as 3. part a.) of the question is unsure...can u help with an answer please...

## Answers and Replies

ehild
Homework Helper
Hi, Krishna,

Can you show a picture, and your work, please? You must be on the right track, as the image is virtual.

ehild

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sure...i will take a snap of it and share it here..can u download the files plz..then u zoom on it for better view...sorry for the scrap i written...but am a poor student...that already embarrasses me

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ehild
Homework Helper
Is the magnification not defined as the seize of the image divided by the seize of the object ?

I do not see if you did anything to find the image of A. See my drawing.
What is the object distance for the red object? Note, that the length of the pinl=1 cm. Find the position of A' and determine the length A1B' to get the magnification.

ehild

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• mirror.JPG
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can u help me with a work solution for this time please?

ehild
Homework Helper
I do not understand what is a work solution you expect from me. I am just trying to help. The point A is at the peak of the red arrow in my previous picture. Determine the position and size of the image of the red arrow: Its peak is the image of A.
For that, you need the object distance, do, it is shorter than it was for B. Therefore, the magnification will be different for A and B.

ehild

okki, i got it, am off to my desk to work it out ehild..thanks.