05-01-2018, 04:50 PM
*Sea and land breezes can be explained on the basis of convection.
*Ocean currents, Monsoons and Trade winds are based on the principle of convection.
*Transmission of heat from one point to another without heating the medium is called radiation.
*The Change of vapour into liquid state is known as
Ans : Condensation
*Solar energy reaches earth through radiation.
*The main source of our energy
Ans : Sun
Thermos flask (vacuum flask)
*Thermos flask was invented by - Sir James Dewar
*Vacuum flask works with the help of a vacuum between “2- glass containers which will prevent the heat loss.
*Vacuum prevents heat loss by conduction and convection.
*The polished shining surface inside and outside of vaccum prevents heat loss by radiation.
*Thermosflask usually holds the contents below the boiling-point Of water.
*Glass used to make thermos flask -Borosilicate glass.
*Almost every liquid expands with the increase in temperature. But when the temperature of water is increased from 0°C to 4°C the volume decreases. If the temperature is increased above 4°C the volume starts increasing. This is called anomalous expansion of water.
*The temperature at which water has least
volume and high density = 4^0C
Density = Mass/Volume
*When water is heated from CPC to 10°C its volume decreases first and then increases.
*Water expands on freezing. During the winter season water pipes, break in cold regions due to this reason.
*When water filled in a bottle is allowed to freeze, the bottle breaks.
Thermal Expansion
*Tendency of matter to change in volume in response to change in temperature is called as
Ans : Thermal Expansion
*Mercury Thermometer works on' the principle of
Ans : Thermal Expansion
*All substances expand on heating.
*Gases expand most when heated.
*Solids have the least expansion on heating.
*Liquid expand more than solid on heating
