JSIERT

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.

From the sun the heat comes to us by this process is known as radiation. The transfer of heat by radiation does not require any medium. It can take place whether a medium is present or not. A hot utensil kept away from the flame cools down as it transfers heat to the surroundings by …

What is radiation ? Read More »

At night it is exactly the reverse. The water cools down more slowly than the land. So, the cool air from the land moves towards the sea. This is called the land breeze.

During the day, the land gets heated faster than the water. The air over the land becomes hotter and rises up. The cooler air from the sea rushes in towards the land to take its place. The warm air from the land moves towards the sea to complete the cycle . The air from the …

What is sea breeze? Read More »

When water is heated, the water near the flame gets hot. Hot water rises up. The cold water from the sides moves down towards the source of heat. This water also gets hot and rises and water from the sides moves down. This process continues till the whole water gets heated. This mode of heat …

What is convection ? Read More »

The materials which do not allow heat to pass through them easily are poor conductors of heat such as plastic and wood. Poor conductors are known as insulators.

The materials which allow heat to pass through them easily are conductors of heat. For examples,aluminum, iron and copper.

The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.

§ should be kept upright not tilted. § bulb should be surrounded from all sides by the substance of which the temperature is to be measured. The bulb should not touch the surface of the container.

A clinical thermometer reads temperature from 35°C to 42°C.