Arrange the energy conversion processes in the following in order from the least to the most efficient: (A) Electric hot water heater (B) Photosynthesis (C) Solar cell (D) Electric generator (E) Aircraft jet engine
Choose the correct answer from the options given below:

Correct option is D

Explanation:
Let’s evaluate the efficiency of each process:
1. (B) Photosynthesis:
· Efficiency is very low, typically around 1–2%.
· Plants convert sunlight into chemical energy slowly.
2. (C) Solar cell:
· Solar photovoltaic (PV) efficiency ranges around 15–22% for commercial panels.
· Better than photosynthesis but still relatively low compared to mechanical systems.
3. (E) Aircraft jet engine:
· Jet engines convert chemical energy (fuel) to kinetic energy.
· Efficiency ~ 25–35%, depending on design and operation.
4. (D) Electric generator:
· Very efficient; converts mechanical energy to electrical.
· Efficiency ~ 90–98% for modern generators.
5. (A) Electric hot water heater:
· Though it converts 100% electrical energy to heat, it's not an efficient energy conversion system in broader thermodynamic terms because it starts from already processed energy (electricity).
Information Booster:
· Efficiency here considers primary energy input to useful energy output.
· Electric heaters are efficient in isolation, but inefficient in system-wide energy conversion when electricity is derived from thermal sources (like coal).