# 1.1.16 Improving Efficiency

Higher Tier Only

### Improving Efficiency

• The efficiency of a device can be improved by reducing the amount of unwanted energy that is produced (usually heat, light or sound)
• Machines waste energy due to:
• Friction between their moving parts
• Air resistance
• Electrical resistance
• Noise

#### Reducing Friction

• In a mechanical system, for example, there is often friction, which can result in unwanted heat being produced
• This friction can be reduced by:
• Adding bearings to prevent components from directly rubbing together
• Lubricating parts

#### Reducing Electrical Resistance

• Electrical systems can also produce heat due to the presence of resistance
• High resistance within electrical components can cause them to become very hot
• Heat loss can be reduced by:
• Using components with lower resistance
• Lowering the current to reduce the amount of heat produced

#### Reducing Air Resistance

• Air resistance causes a force between the moving object and the air that opposes its motion
• Heat is produced as a result and is lost to the surroundings
• Heat loss can be reduced by:
• Streamlining the shapes of moving objects
• For example, a racing cyclist adopts a more streamlined posture to reduce the effects of air resistance
• Also, the bicycle, clothing and helmet are designed to allow them to go as fast as possible

Many factors such as posture, clothes and bicycle shape must be considered when trying to reduce air resistance

#### Reducing Noise

• Sound created by machinery causes energy transfer to the surroundings
• This noise can be reduced by:
• Tightening loose parts to reduce vibration
• Lubricating parts

#### Exam Tip

When answering questions about improving efficiency, it is helpful to identify the useful energy output and the wasted energy output(s). Remember, the efficiency of a device is improved by increasing the USEFUL energy output of the device.

### Author: Ashika

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.
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