Question

Convection currents in liquid or gas is due to:
(A) Change in mass of fluid
(B) Change in volume of fluid
(C) Change in density of fluid
(D) All of the above

Answer 1

Hint: Convection current depends on the physical quantity which tells us how heavy or light a substance can be for a given size. Generally, the hot particles rise up while the cooler ones sink down.

Complete answer:
-To begin with, let us discuss something about the term ‘convection’. Convection is a method of heat transfer. Matter is transferred from one position to another as currents are generated. So, this is a method of mass transfer as well. Naturally occurring convection is called natural convection or free convection. It's called induced convection if a fluid is pumped using a fan or a pump.
-A differential in temperature allows objects to shift, forming a current. A temperature differential between gases and plasma also contributes to higher and lower density regions where atoms and molecules migrate to fill between low pressure zones. In brief, while cold fluids sink, hot fluids rise. Unless a source of energy (e.g., sunlight, heat) is present, convection currents only proceed until a uniform temperature is reached.
-Convection currents are moving fluids when there is a change in temperature or density inside the substance. But however, convection currents do not depend on the mass or volume of the fluid, as these two quantities are constant in case of a given fluid.

The correct option is C.

Note: It is important to remember that there are many phenomena of convection currents that we are observing in day to day life. An instance of a convection current is wind. Heat radiates from sunshine or reflecting light, making up a temperature difference that allows the air to shift. Shady or damp areas are colder, adding to the effect, or capable of absorbing heat.