Efficiency

This lesson covers: 

  1. Defining efficiency and its calculation
  2. The importance of efficiency in minimising energy waste
  3. Calculating efficiency using energy input and output

Efficiency

The concept of efficiency is central to understanding energy usage. It measures how well energy is converted into useful work or output, rather than being wasted. It's a way of quantifying how much of the input energy is effectively utilised for the desired task.

The formula for calculating efficiency is simple yet informative:


Efficiency % = total input energyuseful output energy×100

Worked example - Calculating efficiency of a solar panel

Calculate the efficiency of a solar panel that converts 500 J of solar energy into 150 J of electrical energy.


Step 1: Formula

Efficiency(%)=Total input energyUseful output energy×100


Step 2: Substitution into the equation

Efficiency(%)=500150×100=30% 

The importance of efficiency

Efficiency is more than just a number; it has profound implications:

  • Conserving resources - higher efficiency means more effective use of energy, which can lead to conservation of natural resources.
  • Environmental impact - efficient energy use can reduce harmful emissions and lessen the environmental footprint of energy production.
  • Cost-effectiveness - efficient technologies can lower the costs associated with energy production and consumption.


However, it's important to understand that achieving 100% efficiency is theoretically impossible due to the second law of thermodynamics, which implies that some energy will always be transformed into unusable heat.