Question

Why is it hotter for the same distance over the top of a candle than it is on the side of its flame?
(A).Conduction of heat in air is upward
(B).Heat is maximum radiated in upward direction
(C).Radiation and conduction both contribute in transferring heat upwards.
(D).Convection takes more heat in upward direction.

Answer 1

Hint: The hot air is less dense or lighter than the cooler air all over the place it, so it naturally goes upward, making the area above the flame that is hotter than the area to the sides of it.

Complete answer:
The side of the fire we are getting the radiant heat from the burn. On the top we get the temperature change in the hot air and the actual burn chemicals arise with the less dense air.

So, the option (D) is correct.

Note:
We know that the heat transferred by the three methods:
First one is radiation; the infrared waves travel outwards from the heat source and produce the heat when they are soaking up by an object.
Second one is conduction; the heat energy released is moving directly from the molecule to that molecule, each molecule heating the next. In solids, it is most effective.
Third one is convection; it is only applicable to liquids and gases. While the heat is soaked up by molecules, it’s near the heat or in the heat source by the conduction.
In an open fire, the only radiation and the convection methods are significant for the transfer of the heat. When the hand is next to a fire, we feel the heat from that radiation. It is appreciable but not as that intense, as the heat is directly above to the fire.