Question

The coefficient of performance (COP) of a refrigerator is defined as:

• A. Work done heat removed
• B. Heat removed from cold body work supplied
• C. Heat supplied work output
• D. Heat rejected heat absorbed

Hint:

Logic Tip: It's exactly like calculating gas mileage for a car. You want maximum cooling (Heat removed) for the minimum amount of electricity on your power bill (Work supplied).

Answer 1

The Correct Option is B

Concept:
The Coefficient of Performance (COP) is the standard metric for measuring the efficiency of refrigeration cycles and heat pumps. Like most engineering efficiency metrics, it is a ratio of "desired output" to "required input".

Step 1: The primary purpose of a refrigerator is to cool an enclosed space. Therefore, the desired output is the amount of heat extracted or removed ($Q_{cold}$) from the cold body.

Step 2: To force heat to move unnaturally from a cold space to a hot room, you must input electrical/mechanical energy via a compressor. This is the work supplied ($W_{in}$).

Step 3: COP is mathematically defined as the desired cooling effect divided by the required work input: $COP = \frac{Q_{cold}}{W_{in}}$.