Question

Calculate the number of images formed when an object is placed between a pair of mirrors placed 20 cm apart ​

Answer 1

Answer:

Explanation:

When one talks about image on a mirror, one must understand what an image is. When light from an object hits the surface of the mirror and reaches your eyes, you can see that object on the mirror.

So by very definition, if you want to talk about images formed by a pair of mirrors separated by 40 cm, we have more factors at play over here other than just the distance factor in between them, namely the angle between the mirrors, the position of the source of light or the object that you want see an image of in the mirror, the size of the mirrors, the size of the object, and your position relative to the object and the mirror.

Now considering your question, you are probably looking an answer to two mirrors placed parallel to each other and an object placed exactly in between them, and the answer you are searching for is something like "an infinite amount of images" - but you would be wrong.

Consider the only parameter we did not consider in the above question - your position relative to the mirror and object. You could be at such an angle and position relative to the mirror that light from the object reflected off both mirrors might not reach you at all, in which case, you might not see any image.

And considering the other extreme, suppose you yourself are the object and standing exactly in between the two mirrors, and consider yourself to be a point(not a full sized object), you would see only 1 image of yourself in the mirror in front of you - because for multiple images, the light from "your reflection" would need to get reflected off the mirror behind you and again from the mirror in front of you and then reach your eyes. Which would not be possible in this case since, you being only a point, light from you hitting the mirror in front of you perpendicularly would reflect right back to you and getting absorbed or reflected off you again. In this scenario, light from you has no chance of hitting the mirror behind you and reflecting back to you, no matter what angle the light is at when reflecting off the mirror, since you are a point sized object.

Now, considering you are viewing an object placed in between the mirrors and you can actually see the image, in this case, the number of images would range from 1 to X (X being a very large number depending on your position relative to the mirror and object, and X not infinity). It is interesting to note here that if you had the two mirrors of infinite size and the surfaces perfectly reflecting, and your eyes which are capable of resolving images coming from infinite distance away, then you might see an infinite number of images as depicted below (just imagine the mirrors to extend infinitely):