NCERT solutions for Science [English] Class 7 chapter 11 - Light [Latest edition]

An image that cannot be obtained on a screen is called ______.

Image formed by a convex ______ is always virtual and smaller in size.

An image formed by a ______ mirror is always of the same size as that of the object.

An image which can be obtained on a screen is called a ______ image.

An image formed by a concave ______ cannot be obtained on a screen.

We can obtain an enlarged and erect image by a convex mirror.

A concave lens always forms a virtual image.

We can obtain a real, enlarged and inverted image by a concave mirror.

A real image cannot be obtained on a screen.

A concave mirror always forms a real image.

Match the items given in Column I with one or more items of Column II.

State the characteristics of the image formed by a plane mirror.

Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.

What is a virtual image? 

Give one situation where a virtual image is formed.

State two differences between a convex and a concave lens.

Give one use each of a concave and a convex mirror.

Which type of mirror can form a real image?

Which type of lens forms always a virtual image?

A virtual image larger than the object can be produced by a ______.

David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be ______.

The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the image of truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be ______.

Play with a mirror

Write your name with a sketch pen on a thin sheet of paper, polythene or glass. Read your name on the sheet while standing in front of a plane mirror. Now look at your image in the mirror.

A burning candle in water

Take a shoe box, open on one side. Place a small lighted candle in it. Place a clear glass sheet (roughly 25 cm × 25 cm) in front of this candle figure. Try to locate the image of the candle behind the glass sheet. Place a glass of water at its position. Ask your friends to look at the image of the candle through the sheet of glass. Ensure that candle is not visible to your friends. Your friends will be surprised to see the candle burning in water. Try to explain the reason.

Make a rainbow

Try to make your own rainbow. You can try this project in the morning or in the evening. Stand with your back towards the Sun. Take a hosepipe or a water pipe used in the garden. Make a fine spray in front of you. You can see different colours of rainbow in the spray.

Visit a laughing gallery in some science centre, or a science park or a village mela. You will find some large mirrors there. You can see your distorted and funny images in these mirrors. Try to find out the kind of mirrors used there.

Visit a nearby hospital. You can also visit the clinic of an ENT specialist, or a dentist. Request the doctor to show you the mirrors used for examining ear, nose, throat and teeth. Can you recognise the kind of mirror used in these instruments?

Role play

Here is a game that a group of children can play. One child will be chosen to act as object and another will act as the image of the object. The object and the image will sit opposite to each other. The object will make movements, such as raising a hand, touching an ear etc. The image will have to make the correct movement following the movement of the object. The rest of the group will watch the movements of the image. If the image fails to make the correct movement, she/he will be retired. Another child will take her/his place and the game will continue. A scoring scheme can be introduced. The group that scores the maximum will be declared the winner.