# NCERT Class VII Science Solutions: Chapter 15 – Light Part 3

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Question 14:

Boojho made light from a laser torch to fall on a prism. Will he be able to observe a band of seven colours? Explain with a reason.

No, laser torch gives out light of only one colour.

Question 15:

State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B. shown in Figure.

Question 16:

The side mirror of a scooter got broken. The mechanic replaced it with a plane mirror. Mention any inconvenience that the driver of the scooter will face while using it?

The driver will not be able to see traffic spread over a large area behind him.

Question 17:

The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from the torch?

The beam of light will be diffused with lower intensity.

Question 18:

An erect and enlarged image of an object is formed on a screen. Explain how this could be possible.

The image formed on the screen could be enlarged and erect if the object is placed upside down between F and 2F of the lens.

Question 19:

Two different type of lenses are placed on a sheet of newspaper. How will you identify them without touching?

If the letters appear bigger/magnified, then the lens is a convex lens. If the letters appear smaller, then the lens will be concave lens.

Question 20:

A shopkeeper wanted to fix a mirror which will give a maximum view of his shop. What type of mirror should he use? Give reason.