Video Transcript
The following figure shows an
object reflected in a plane mirror. The image of the object is seen
by observer A. If the mirror is removed, which
of the following shows the object as it would appear to observer B? (A), (B), (C), or (D).
In this question, we are shown
how the image appears to observer A, and we must determine how the object is
seen by observer B. Observer B views the object
directly, whereas observer A views a reflected image of the object. To answer the question, we can
consider just one of the letters of the word “AMBULANCE.” The letters are not all equally
useful for this purpose. The most useful letters are
those that are the least symmetrical. Let us compare some letters to
see how symmetrical they are. The letter L is the least
symmetrical. We want to use the least
symmetrical letter, so we will use L.
Let us consider how light rays
reach the eye of observer A to make the letter L appear as it does in the
image. Now let us consider the paths
that light rays from the object that forms the image of the letter L must have
traveled to the mirror. If we now remove the mirror,
observer B would see light rays from the L directly. We can compare the object L seen
by observer B to the image L seen by observer A.
Now that we know what the object
L looks like, we can look at our answer options to see which of the options
shows the letter L in the same orientation as the object L. The L in option (A) looks the
same as the object L, so this might be the answer we are looking for. To be certain, let’s look at the
other options. The L in option (B) is not the
same as the object L, so option (B) is incorrect. The L in option (C) is not the
same as the object L, so option (C) is incorrect. The L in option (D) is not the
same as the object L, so option (D) is incorrect.
Therefore, option (A) must be
the correct answer. This is the word “AMBULANCE” as
it would appear to observer B if the mirror is removed.
