This blog has been designed to en kindle the enthusiasm of science in students.
"Beleive in yourself and all that you know that there is something inside you that is greater than any obstacle." ---Christian D. Larson
Teapots have shiny surface and since shiny surfaces are bad emitters of radiation, shiny teapots are able to keep the liquid in it warm for a longer period of time as compared to black-coloured teapots.
And in addition, shiny surfaces are bad absorbers, thus shiny teapotsor container can keep cold liquid cold for a longer period of time.
Greenhouses are used in cold climates to help grow plants by trapping heat.
Daytime, infared radiation from the sun pass through glass roof into the greenhouse.
This warm up the plants and help them grow. However, the plants tooemits infared radiation but the infared radiation emitted is different and cannot pass through the glass roof thus it gets trapped inside.
Overtime, the temperature in the greenhouse will increase.
The main use of the vacuum flasks is to keep the liquid in it hot by minimising the loss of heat.
And it is done through 4 possible ways: conduction, convection, radiation and evaporation.
-The stopper of the vacuum/thermos flasks is usually made of plastic which is a poor conductor of heat.
-Conduction will not take place in the trapped air since air is a poor conductor of heat.
-Conduction and convection also cannot take place through the sides as there is a vacuum between the double-glass walls of the flask.
-And to prevent radiation, the walls of the glass are silvered to radiant heat back into the hot liquid to keep it hot.
-The only time conduction and convection can occur is when the plastic stopper is removed.
-However, heat loss through radiation is hard to stop as radiant heatcan even pass through vacuum.