Question

Which of the following letters will be seen with some change in a plane mirror?
A. M
B. T
C. L
D. W

Answer 1

Hint: Recall that a plane mirror produces an apparent left-right inversion of images. This phenomenon is prominent for those objects that are asymmetric about their longitudinal axis. Think of which of the above alphabets are symmetric and this should lead you to the alphabet that might appear inverted upon reflection by a plane mirror.

Complete answer:
We know that a plane mirror, which is basically a flat reflective surface, always produces images that are laterally inverted. This means that there is an apparent reversal of left and right, but this does not mean that the image is upside down. The image is upright but is flipped from left to right.
The figure shows how the alphabets given in the options would appear when placed in front of a plane mirror, with the arrows representing the longitudinal axis, representing their lateral symmetry.

Since a plane mirror always produces images that are inverted about their lateral axis, the implication of this lateral inversion is more profound for those objects that are laterally asymmetric.
From the figure we see that the alphabets M, T and W are symmetric about their longitudinal axis. Although there is lateral inversion it is not evident due to their laterally symmetrical nature. However, if we take the letter L which has no axis of symmetry, we see that the image of L appears to be flipped from left to right. If we take the open end of the horizontal line of L to be on the right side of the object, then the same end appears to be on the left side of the object, as is evident from the figure.

Thus, the correct choice would be C. L.

Note:
Remember that lateral inversion is just an apparent effect that is caused not due to the physical characteristics of the plane mirror but only due to how our brain processes the orientation of images. This is because all that the plane mirror does is reflect the light from the object placed in front of it and produce an image. But our perception of this image as if we were on the other side of the mirror induces this apparent sense of inversion.
This is also the same reason why the word AMBULANCE is painted left-right inverted on the front so that when the driver of a vehicle that is ahead of the ambulance looks into his rear-view mirror, he can make out the work quickly and give way to the ambulance.