Chapter 4: Heat Class 7 Notes (Short Notes)

Heat Class 7 Notes

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Define Heat

What is Heat?

It is a form of energy that is transferred from a body or pint at higher temperature to the body or point at lower temperature.

Also Read: Chapter 7 Class 7 Weather, Climate and Adaptations of Animals to Climate Notes

What are the source of Heat?

Anything that gives off heat is a source of heat.

Examples of some Sources of Heat are- Sun, Wood, Gas, Electricity, Friction

Note: The Sun is the ultimate source of energy.

Temperature

What is temperature?

Temperature is that physical quantity which tells us how hot or cold a body is.

The degree of hotness and coldness is measured in terms if its temperature.

Temperature is measured with the help of a device called Thermometer.

What is the SI Unit of temperature?

The SI Unit of temperature is Kelvin (K).

The other units of temperature are Celsius, Fahrenheit.

What is a Clinical thermometer?

The thermometer that measures our body temperature is called a Clinical thermometer.

The temperature range of clinical thermometer is from 35º C to 42º C.

Note: The normal temperature of human body is 37º C.

Laboratory Temperature

The thermometer that is used in the laboratories.

The range of a laboratory thermometer is generally from –10° C to 110° C.

Heat Transfer

Heat is transferred from one point to other point when there is a temperature difference.

There are three modes of Heat Transfer-

1. Conduction
2. Convection

Conduction

When heat is transferred without the actual movements of molecules. In solids heat is transferred through Conduction process.

What are Conductors?

Conductors are the materials which allow the heat to pass through them comfortably.

Give examples of Good Conductors?

The examples of some good conductors of heat are- generally all metals like Copper, Iron, Aluminum etc.

What are Insulators?

Insulators are the materials which do not allow the heat to pass through them easily. The poor conductors of heat are also called Insulators.

Give some examples of poor conductors of heat or Insulators?

Some poor conductors of heat are- wood, plastic, paper etc.

Note: Water and Air are considered poor conductors of heat.

Convection

The mode of heat transfer where the molecules actually transferred in bulk. Convection mode of heat transferred takes place in the fluids.

This is the third type of heat transfer. The heat is transferred in the form of electromagnetic waves or simply waves.

The heat transfer through Radiation doesn’t require a medium. The heat of the Sun reaches us through the process of Radiation.

Sea Breeze

What is a Breeze?

Breeze is a pleasant wind.

What is Sea Breeze?

It is the movement of the cold air from the sea towards the land.

Sea Breeze is seen during the day.

How Sea Breeze occurs?

During the day, the Sun is out and the land gets heated faster as compared to the water. The air over the land becomes hotter and we know that hot air moves up. Now, the air over the sea is cooler so it rushes in towards the land to take its place. in that process, to complete the cycle, the warm air from the land moves towards the sea.

Land Breeze

What is Land Breeze?

It is the movement of the cool air towards the sea is called Land Breeze.

The Land Breeze is observed during the night near the coastal regions.

During the night the land cools down faster than the sea. The air above the sea is hotter and as we know hot air rises up. So, the cold air above the land takes its place.

We hope you liked these Heat Class 7 Notes.

Also Read: Chapter 14 Electric Current and its Effects Class 7 Notes