Efficiency describes how effectively a system converts input energy into useful output energy. It is expressed as a ratio or percentage, calculated by:
Efficiency = (Useful Output Energy / Total Input Energy) × 100%
Key points:
- An efficiency of 100% means no energy is wasted, which is ideal but rarely achievable in real systems.
- In practical systems, some energy is usually lost as heat, sound, or friction, reducing efficiency.
Examples:
- A car engine might convert only about 30% of the fuel’s energy into motion — the rest is lost as heat.
- LED bulbs are more efficient than incandescent bulbs because more of their input energy becomes light rather than heat.
Understanding efficiency helps in improving designs, reducing waste, and saving energy in everything from machines to electrical systems.