Question

In an experiment of convection heat transfer, water inside the pipe is heated by which of the following principles.
A. free convection \[ + \] conduction
B. free convection
C. forced convection
D. mixed convection

Answer 1

Hint:We need to know what convection is and what conduction is. From the definition of the convection and conduction we can easily give the answer of this question. In which process heat can transfer through a gas or any liquid like the hotter part will rise up and the cooler part which I heavier will sink, is called convection. Gravity is the natural or free convection.

Complete answer:
When the pipe is heated by conduction method, the water inside the pipe is also heated as the water is directly connected to the pipe. The bottom surface of the heated pipe will achieve higher temperature and for that the water of the bottom surface of the pipe also becomes hotter and less dense. Less dense water is lighter so it will move up and the colder water which is heavier and denser will come down and then the convection will set up. So, in the experiment of convection heat transfer, water inside the pipe is heated by free convection and conduction.

Hence, option A is correct.

Note: We can get confused by the definition of convection and conduction. Without any brief knowledge about convection and conduction one cannot answer this question correctly. The example of free and natural convection is the phenomena of the sea breeze during the day time