Science Do as instructed[4M]

1. Vacuum
2. metal/plastic jar
3. Spring
4. silvered surface of the glass.

2.As there is no medium in the vacuum between the two bottles, no transfer of heat takes place due to conduction and convection and radiated heat is reflected back by the shiny surface.
3.The temperature of substances inside it are maintained for some time. Hot things remain hot and cold things cold for 2 – 3 hours..
4.It is a camera which uses radiations to make our surroundings visible at night. Using this camera, it is possible to keep a watch on the movements of the enemy during the night.
5.Thermoware are object which do not allow heat to escape from them. So things stay warm in them. eg. hot pot, thermos flask.

1. Conduction: The transfer of heat from one end of a solid substance to the other, without the particles leaving their original place is called conduction.
2. Convection: Transfer of heat in fluids due to formation of currents is called convection.
3. Radiation: Transfer of heat in all directions in the absence of a medium is called radiation.
4. Transfer of heat: The flow of heat from one place to another is called transfer of heat.