One of the heating systems we talked about in this course comprises of a system of ducts. what is the process by which heat is transferred in this system?

a. conduction
b. convection
c. radiation
d. none of the above

b- covection

Explanation:

Conduction: It is the circulation or transfer of heat through a metal or solid. For example, heat generated inside an enclosure can be transferred to the outer surface by means of conduction.so therefore conduction can not be the answer.

Convection is the circulation or tansfer of heat from a surface by means of a fluid such as air. Natural convection happens when air is heated: it expands, rises, and is replaced by cooler air. The amount of convection may be increased by using a fan to increase the flow of air.Likewise,Ducts are used to circulate air in the system. Since, air is circulated in the system, heat is transfered by convection.Hence,the answer is B-convection.

Radiation: Here, energy is radiated through the air by means of electromagnetic radiation. Since heat transfer through raidation does not involve contact between the heated object and the heated source,so energy is lost as light or through electromagnetic radiation. So C is wrong.

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hope this : d