CBSE – 7th Standard Science

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Question Bank – Chapter 15 – Light

Chapter 15

 LIGHT

 

Q.1 What makes things visible to us?

Ans. The objects are visible only when light reflected from them reaches our eyes.

 

Q.2  Why the word AMBULANCE is  written  inverted?

Ans. When the driver of a vehicle ahead of an ambulance looks in rear view mirror, can read AMBULANCE written on it and give way to it. It is the duty of every one of us to allow an ambulance to pass without blocking its way. We might have observed that in the side mirror of a scooter or a car the images of all the objects appear smaller than the objects themselves.

 

Q 3. State the characteristics of the image formed by a plane mirror.

Ans. An image formed by a plane mirror is erect and of the same size as the object but the right appears left and the left appears right, only sides are interchanged.

 

Q4.  What is a virtual image? Give one situation where a virtual image is formed.

Ans. The image formed by a plane mirror is not real, it could not be obtained on a screen. Such images are called virtual image.

 

Q 5. What is a Lens?  

Ans. The lenses are transparent glass. light can pass through them  magnifying glass is actually a type of a lens, there two types of lenses convex and a concave lens.

  

Q6. State the difference between concave and convex lens?

Ans. A convex lens bends the light inward generally falling on it so it is called converging lens, but a concave lens bends the light outward so it is called a diverging lens.

 

Q7. What happens when the object is placed very close to the convex lens?

Ans. The image of object formed is virtual, erect and magnified when it is placed very close to convex lens.

 

Q8. Give one use each of a concave and a convex mirror.

Ans. Doctors use concave mirror and also in the headlight of cars while convex mirror are used in Side mirror of vehicles .

 

Q9. Which type of mirror can form a real image?

Ans. Plane mirror can form a real image that is erect and of the same size as the object .

 

Q10. Which type of lens forms always a virtual image?

Ans. The image formed by a concave lens is always virtual, erect and smaller in size than the object.

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