Question

“The spoon is rinsed in running cold water. Heat gets absorbed by the water and the spoon gets cooler, until the spoon and the water are at the same temperature” is an example of which of the following way of heat transfer?

(a) Conduction

(b) Convection

(c) Radiation

(d) Filtration

This question was addressed to me during a job interview.

This intriguing question originated from Heat Exchangers in section Building Blocks of Dairy Processing of Dairy Engineering

Answer 1

Right choice is (b) Convection

Easiest explanation: Convection consequently involves mixing. When the teaspoon is rinsed with running cold water, heat gets transferred from the spoon to the water, which is heated in the process. The heated water when replaced by cold water, which in turn absorbs heat from the spoon. Heat transfer by convection continues until the spoon and the running water have the same temperature.