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An image is an illusion created with light. To understand images, ask yourself why you can see the same point on a ball from many angles? The answer is that light from each point on the ball spreads out in all directions. Your eye captures those rays that happen to enter your pupil and forms the image of that point of the ball on your retina. An image is an organization of light rays that has the same spatial pattern as the original light rays coming from the actual object. 
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Consider the reflected image of the ball in a flat mirror. Three light rays that leave point A on the ball are reflected from the mirror. For each of the three rays, the law of reflection gives the direction of the reflected ray (angle of reflection equals angle of incidence). The reflected rays appear as if they came from point B behind the mirror! Point B is where you see the image of point A.
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The image in a mirror forms because multiple rays from the same point on an object appear to come from a single point somewhere else. Your eye sees the exact same organization of light in the reflected rays as it would if the ball were actually at the image location. Your visual system does not sense “mirror” and perceive things as a reflection. Instead, your visual system receives just light rays. If the light rays appear to come from behind the mirror, then you “see” the ball at that point behind the mirror (the image).
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Look carefully at the illustration above: The image of the ball appears behind the mirror at a distance equal to the actual ball’s location in front of the image. The distance between the mirror and the ball is the object distance, while the distance between the mirror and the ball’s image is the image distance. For reflection in a flat mirror, the image and object distances are equal.
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The next time you look in a mirror notice that your image appears to have left and right sides reversed, as if you were standing facing yourself. Try raising your left hand. Your image will raise the hand on your left, which is the image’s right hand. To understand why this happens, consider the reflection of the letter “F” (illustrated at right). Point A on the right-hand side of the object appears at point B on the left-hand side of the image.
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If you are standing 2 m in front of a flat mirror, how far away from you is your image in the mirror? - 0 m
- 1 m
- 2 m
- 4 m
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The answer is d, 4 m. If you are 2 m in front of the mirror, then the image is 2 m behind the mirror, making it 4 m away from you. 
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