# Homework Help: Nature of image formed by a plane mirror

1. Jun 2, 2006

### Amith2006

Sir,
1) A beam of light incident on a plane mirror forms a real image on reflection. It is said that the incident beam in that case is convergent. Is it true?
I think it is due to the fact that a plane mirror normally forms virtual images of real object. In order that a real image be formed by it, the object should be virtual and only a convergent beam of light can produce a virtual object. Is my argument right?
2) What is the nature of the picture seen on the screen of a pin hole camera? Is it an image or a Shadow?
I think it’s an image. What do you say Sir?
3) A ray reflected successively from 2 plane mirrors inclined at a certain angle undergoes a deviation of 300 degrees. How many images are observable?
I solved it in the following way:
We know that the deviation produced by 2 plane mirrors inclined at an angle y is 180 + 2y.
Therefore 180 + 2y = 300
y = 60
Here it is assumed that the object is placed symmetrically between the 2 inclined mirrors. We know that number of images observed = (360/y) – 1
= 5
Is it right?

2. Jun 3, 2006

### Andrew Mason

The rays from an object always diverge. The plane mirror does not change the divergence - they just reflect them. A real image is formed by converging rays. A virtual image is one that appears to originate at the point the rays start diverging.
Why do you think it is an image? You have a 50-50 chance just by guessing. You have to explain your reasoning.

Amith,

What is with the "Sir"? This is an equal opportunity board! Women can respond too.

AM

3. Jun 3, 2006

### Amith2006

Sir,
I guessed this because a pin hole camera forms an inverted image and the shadow of an upright object will never be inverted. You didn't say anything about the 3rd question. I will certainly introduce the F factor in my future queries.