EN हिं

NCERT Solutions Curiosity Chapter 11 .6 Images Formed in a Plane Mirror — Activity 11.7: Let us experiment

Book page 16111 Updated on2026-09-05

Q1.
Place the pen in front of the mirror as shown in Fig. 11.10. What do you see in the mirror?
Answer

A second pen is seen, standing behind the mirror, looking exactly like the real one.

The pen you have kept on the table is the object; the pen that seems to be behind the mirror is its image formed by the mirror.

Why it happens: Light from every point of the pen falls on the mirror and is reflected to your eye. The reflected rays reach your eye as if they had started from a point behind the mirror. There is really no pen there — but your eye cannot tell the difference, and you see an image.
Q2.
Now, move the pen to different positions in front of the mirror and compare the sizes of the images of the pen at each position. Are the two sizes the same?
Answer

Yes. At every position the image is exactly as big as the pen itself.

size of image = size of object

Bring the pen close to the mirror or take it far away — the image never grows or shrinks compared with the object.

Check it yourself: Hold a 15 cm scale against the mirror. Its image also reads 15 cm long. This is why a plane mirror is the right mirror for dressing up, and why a curved mirror (like the back of a steel spoon) is not.
Q3.
Again, move the pen to different positions in front of the mirror and observe if the image is upright at each position. Does the tip of the pen appear on top at each position?
Answer

Yes. The tip of the pen appears on top in the image at every position — the image is never upside down.

An image whose top and bottom are the same way up as the object's is called an erect image. The image formed by a plane mirror is erect.

Tip: Do not confuse erect with unchanged. The mirror image is the right way up, but it is still turned round left-to-right — that is lateral inversion, which you meet in Activity 11.8.
Q4.
Now, place a screen vertically behind the mirror. Move it around. Do you get the image on the screen? Repeat this by placing the screen in front of the mirror.
Answer

No. The image cannot be caught on the screen — neither behind the mirror nor in front of it. The screen shows nothing, however you move it.

Why it happens: The reflected rays do not really meet behind the mirror; they only appear to come from there. Since no light actually reaches the place where the image seems to be, there is nothing for a screen to catch. Such an image is called a virtual image — the image formed by a plane mirror cannot be obtained on a screen.
Compare: The pinhole camera of Section 11.7 is the opposite case — there the rays really do meet on the tracing paper, so that image can be caught on a screen.
Was this helpful? Report an error