Heat | Speed Notes

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Heat: It is a form of energy, which makes any object hot or cold.

The materials which allow heat to pass through them easily are conductors of heat.

The materials which do not allow heat to pass through them easily are called insulators.

Temperature: The degree of hotness of an object is called temperature.

Heat is the cause of temperature.

Our sense of touch is not reliable to measure the temperature. (Scroll down to continue …)

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Heat:

It is a form of energy, which makes any object hot or cold.

Temperature: The degree of hotness of an object is called temperature. Our sense of touch is not reliable to measure the temperature.

Thermometer is a device used for measuring temperatures.

Heat is the cause of temperature.

Clinical thermometer is used to measure our body temperature.

Transfer of Heat: Heat flows from a hotter object to a colder object until both objects reach the same temperature.

The heat flows from a body at a higher temperature to a body at a lower temperature.

There are three ways in which heat can flow from one object to another.

These are conduction, convection and radiation.

Conduction: It is the process by which heat is transferred from the hotter end to the colder and end of an object.

Convection: It is the flow of heat through a fluid from places of higher temperature to places of lower temperature by movement of the fluid itself.

Radiation: It is the mode of transfer of heat in which energy is directly transferred from one place to another.

It does not need any material medium.

Dark-coloured objects absorb radiation better than the light-coloured objects.

That is the reason we feel more comfortable in light-coloured clothes in the summer.

Woollen clothes keep us warm during winter.

It is so because wool is a poor conductor of heat and it has air trapped in between the fibres.

Thermometer:

Thermometer is a device used for measuring temperatures.

Clinical thermometer:

Clinical thermometer is used to measure our body temperature.

A thermometer used to measure the temperature of our body is called a clinical thermometer.

For other purposes, we use the laboratory thermometers.

The range of these thermometers is usually from –10°C to 110°C.

The normal temperature of the human body is 37°C.

It consists of a long, narrow, uniform glass tube with a bulb containing mercury at one end.

There is a kink near the bulb.

The range of clinical thermometer is from 35°C to 42°C. (Or from 94°F to 108°F).

Laboratory Thermometer:

Laboratory Thermometer: It is a thermometer used to measure the temperature of objects other than our body.

It consists of a column of mercury enclosed in a glass casing.

The column is continuous without any kink.

It measures a range of temperature from -10˚C to 110˚C.

Sea Breeze:

Sea Breeze: Durign the day, the land heats up faster than the sea.

Warm air above the land rises and cold air from sea takes its place.

Warm air from the land moves towards the sea to compele the cycle.

This produces a sea breeze from the sea to the land.

Land Breeze:

Land Breeze: At night the land cools faster than sea.

The warm air above the sea rises.

This warm air is replaced by colder air from the land producing a land breeze.