Question

In above shown figure of refrigeration system. Which of the following statement explains why work is an input into this system?

• A. Work is needed to move thermal energy against temperature gradient.
• B. Work is needed to reduce the amount of thermal energy lost during transfer.
• C. Work uses energy from the cold reservoir to reduce the temperature of the system.
• D. Work adds energy to the cold reservoir to increase the heat flow to the hot reservoir.
• E. Work adds heat to the system, causing the temperature of both reservoirs to increase.

Answer 1

The correct option is A Work is needed to move thermal energy against temperature gradient.

In a thermodynamic system, heat naturally flows from hotter body to a colder body. The given figure shows a refrigerator energy flow diagram. The heat flow is opposite to the direction of conventional heat flow and hence external work is required for the given heat flow diagram.