Question

A heat engine absorbs energy from a heat source at 300 K (room temperature in a warm room), turns some of it into electrical energy, and rejects the remainder to a heat sink at a temperature of approximately 0 K (a bucket of liquid helium, for example). The Carnot efficiency of such an engine will be

Answer 1

The Carnot efficiency of a heat engine with a heat source at 300 K and a heat sink at approximately 0 K would be 100%, but this is only theoretical since a heat sink at 0 K is impossible to achieve in practice.

Step-by-step explanation:

The Carnot efficiency of a heat engine is determined by the temperatures of the heat source and the heat sink to which it exhausts heat. Given that the heat source is at 300 K and the heat sink is approximately 0 K, we can calculate the Carnot efficiency using the following formula:

Efficiency = 1 - (Tc/Th)

Where Tc is the temperature of the cold reservoir (heat sink) and Th is the temperature of the hot reservoir (heat source). Here, Tc = 0 K and Th = 300 K. When we insert these values into the formula:

Efficiency = 1 - (0 K / 300 K) = 1 - 0 = 1 or 100%

However, it is important to note that achieving absolute zero temperature (0 K) is practically and theoretically impossible, so the 100% efficiency is also an idealization that cannot be realized in practice. The maximum efficiency is always less than 100%, and for real engines, it is typically around 0.7 times the Carnot efficiency due to other inefficiencies.