CBSE Class 7 Science Light And Water Assignment

A. Short answers:

1. What is the relation between the incident ray, the reflected ray and the surface of a plane mirror?

2. Mention two uses of concave mirror and convex lens.

3. Mention three causes for scarcity of water in our country.

4. Write the nature of image formed when object is -

a. placed beyond the focus of a concave mirror

b. placed beyond the focus of a convex lens

c. at infinity infront of a concave mirror

d. closer than the focus of a concave mirror

e. closer than the focus of a convex lens

f. placed infront of a convex mirror

g. placed in front of a concave lens

5. What are surface water sources?

B. Answer in not more than 40 words:

1. How the pattern of rainfall in our country leads to scarcity of water? Which part of the country gets rainfall twice a year?

2. What do you understand by the spectrum of white light? How is a rainbow formed?

3. What happens when parallel rays of light fall on a curved reflecting surface?

C. Give reasons for the following:

1. All the rain that falls over an area cannot be utilized.

2. Image formed by pinhole is inverted.

3. Newton’s disc appears white when it is rotated.

4. Convex mirrors are used as rear-view mirrors.

D. Answer in 100 words:

1. How did Vilasrao Salunkhe solve the crisis in Naigaon?

2. What are the different ways to get over the scarcity of water?

3. Differentiate between real and virtual image.

4. How will you find the focus of a convex lens?

5. What is refraction? Explain with example.

E. Fill in the blanks:

1. A magnifying glass is a……………lens.

2. A convex mirror is one in which the reflecting surface bulges………………..

3. Shadows are formed due to …………………………….. propagation of light.

4. A drop of water on a leaf forms a magnified image of the veins because of…………

5. A …………… tank allows water to seep into the soil and recharge groundwater.

6. About 50% of our agriculture needs are met by…………..

7. The area from which water drains into a river or stream is its ………….. area.

F. Define the following:

1. White light

2. Soil moisture

3. Water table

4. Precipitation

5. Focus

6. Centre of curvature

7. Reflection

8. Lenses

9. Spectrum

10. Deforestation