Class 4 Science Lesson 7

Exercise

1. Choose the correct option for the following questions.

a) Where do living things get their energy from?
👉 iii. food

b) Which of the following is a source of energy?
👉 i. coal

c) Which of the following vehicles requires a lot of energy?
👉 iii. truck

d) Which of the following is a natural source of energy?
👉 iii. biogas

2. Fill in the blanks with the correct words listed below.

a) Ability to work is called………
👉 energy

b) The sun is the …….. source of energy.
👉 main

c) The aircraft receives energy from …….
👉 fuel

d) Adult people need……..energy than a small child.
👉 more

3. Put the right (√) sign if true and the wrong (X) sign if the statement is wrong:

a) Energy is required to do any work. ✔

b) Plants get energy from the sun. ✔

c) Firewood is not a source of energy. ✘

d) Human beings generate energy from food. ✔

e) Heat energy is considered to be the major source of energy. ✘

4. Match the objects and the sources of energy.

Aeroplane → Petroleum products

Plant → Sun

Television → Electricity

Wall clock → Dry Cell

Human being → Food

5. Answer the following questions:

a) Define energy.

👉 Energy is the capacity to do work.

b) What is meant by the source of energy?

👉 Objects from where energy can be obtained are called sources of energy.

c) Write the names of any four sources of energy.

👉 Sun, food, petrol, dry cell

d) Name any four forms of energy.

👉 Heat energy, sound energy, electrical energy, magnetic energy

e) Write any five importances of energy.

👉 Energy is used to walk, cook food, run vehicles, operate machines, and perform daily tasks.

6. Give reason:

a) The sun is considered to be the main source of energy.

👉 Because it gives us heat and light energy, and plants also make food using sunlight.

b) When we do not eat, we feel weak.

👉 Because we get energy from food, and without energy, our body cannot do work.

7. A big tractor and another small tractor have been used for ploughing a field. Answer the following:

a) Which tractor can plow more field at the same time? Give reason.

👉 The big tractor can plow more field because it has more power and energy.

b) Which tractor requires more diesel to run for an equal time? Why?

👉 The big tractor requires more diesel because it needs more energy to work.

Exercise: Electricity

1. Choose the correct answer.

a) Which of the following devices uses a battery?

👉 iii. torch light

b) What does a solar battery generate electricity from?

👉 iii. sunlight

c) What is hydro-electricity generated from?

👉 ii. water

d) Which of the following sources of electricity is used for generating a lot of electricity?

👉 ii. generator

2. Fill in the blanks using the following words:

a) …….. energy is used to operate a computer.
👉 Electricity

b) Solar light runs from ……..
👉 Solar battery

c) Mobile is a device run by ……..
👉 battery

d) Dry cell is the source of ……..
👉 electricity

3. Put a tick (√) if the statements are true and cross (X) if they are incorrect:

a) Electric energy is used in oil crushing machines. ✔

b) Computers generate electricity. ✘

c) Dry cell is the source of electricity. ✔

d) Dry cell is required to generate electricity from water. ✘

4. Give reasons:

a) Hydro-electricity is considered the major source of electricity in our country.

👉 Because electricity in our country is produced from flowing water by rotating turbines.

b) Electricity is an important source of energy.

👉 Because it is used to run machines, lights, fans, TV, mobile phones and many devices.

5. Answer the following questions:

a) Write the names of any four electrical devices.

👉 Fan, TV, iron, radio

b) What is meant by the source of electricity?

👉 Objects from which electricity is obtained are called sources of electricity.

c) Write any two uses of electricity.

👉 Electricity is used to light bulbs and operate electrical equipment.

d) Write the names of any four sources of electricity.

👉 Generator, dry cell, battery, solar battery

e) How is energy produced from a dynamo?

👉 When the dynamo is rotated, it produces electricity.

f) How is hydro-electricity generated? Explain with a diagram.

👉 Hydro-electricity is generated by using the energy of flowing water. Water turns the turbine connected to a generator, and the generator produces electricity.

👉 (Insert simple labeled diagram: Water → Turbine → Generator → Electricity)

Exercise: Magnet

1. Tick the correct answer for the following questions.

a) Which of the following is a magnetic object?
👉 ii. pen nib

b) Which of the following is a non-magnetic object?
👉 iii. paper

c) In which device is magnet used?
👉 ii. Radio

d) Which of the following facts is true about a magnet?
👉 ii. attraction between unlike poles

e) Which of the following is an example of a conductor?
👉 ii. aluminium

2. Fill in the blanks:

a) A magnet can pull a magnetic object only within its ……..
👉 magnetic field

b) The ability of a magnet to …….. magnetic objects is called magnetic force.
👉 attract

c) An object attracted to a magnet is called …….. object.
👉 magnetic

d) Plastic is a …….. object.
👉 non-magnetic

e) …….. occurs between the like poles of a magnet.
👉 Repulsion

4. Tick (√) if the statements are true and cross (✘) if they are incorrect:

a) Iron is a magnetic object. ✔

b) A magnet is used in the speaker. ✔

c) Non-magnetic objects are attached to the magnet. ✘

d) The pulling capacity of a magnet varies. ✔

e) Independently hung rod magnet always sets east-west. ✘

4. Answer the following questions:

a) Write the names of any three examples of magnetic and non-magnetic objects.

👉 Magnetic: pin, nail, safety pin
👉 Non-magnetic: plastic, wood, eraser

b) What kind of object is called a magnetic object?

👉 An object that is attracted by a magnet is called a magnetic object.

c) Define magnetic force.

👉 The force with which a magnet pulls magnetic objects towards itself is called magnetic force.

d) Write the difference between magnetic and non-magnetic objects.

👉 Magnetic objects are attracted by magnets, while non-magnetic objects are not.

e) Write any four utilities of a magnet.

👉 Magnets are used in TV, speaker, compass, and to pick up small objects like pins and needles.

f) You have two magnets. Describe the process you will follow to compare their strengths.

👉 Use both magnets to attract pins from the same distance. The magnet that attracts more pins or attracts from a greater distance is stronger.

g) Write the three differences between a conductor and a non-conductor of electricity.

👉 Conductor allows electricity to pass; non-conductor does not.
👉 Conductor includes materials like copper, aluminium; non-conductor includes rubber, plastic.
👉 Conductors light the bulb in circuit; non-conductors do not.

h) Some of Neha’s coins fell into a deep pond. She desperately needs these coins. How can Neha retrieve the coin bag without going inside a pond?

👉 Neha can use a strong magnet tied to a string and dip it in the pond to attract the coins made of iron.

i) Write any four properties of a magnet.

👉 It attracts magnetic objects.
👉 It always points north-south when freely hung.
👉 Like poles repel, unlike poles attract.
👉 The poles of a magnet cannot be separated