# 1.1.7 Thermal Energy

### Thermal Energy

• Thermal energy is the energy contained within a system that is responsible for its temperature
• This energy can also be stored in or released from the system
• The amount of thermal energy needed to raise the temperature of a given mass by a given amount can be calculated using the equation:

ΔE = mcΔθ

• Where:
• ΔE = change in thermal energy, in joules (J)
• m = mass, in kilograms (kg)
• c = specific heat capacity, in joules per kilogram per degree Celsius (J/kg °C)
• Δθ = change in temperature, in degrees Celsius (°C)
• The specific heat capacity of a substance is defined as:

The amount of thermal energy required to raise the temperature of 1 kg of a substance by 1 °C

• Different substances have different specific heat capacities
• If a substance has a low specific heat capacity, it heats up and cools down quickly (ie. it takes less energy to change its temperature)
• If a substance has a high specific heat capacity, it heats up and cools down slowly (ie. it takes more energy to change its temperature)

Low v high specific heat capacity

• Specific heat capacity is mainly used for liquids and solids
• The specific heat capacity of different substances determines how useful they would be for a specific purpose eg. choosing the best material for kitchen appliances
• Good electrical conductors, such as copper and lead, are excellent conductors of heat due to their low specific heat capacity
• On the other hand, water has a very high specific heat capacity, making it ideal for heating homes as the water remains hot in a radiator for a long time

#### Exam Tip

This equation will be given on your equation sheet, so don’t worry if you cannot remember it, but it is important that you understand how to use it. You will always be given the specific heat capacity of a substance, so you do not need to memorise the value of any.

### 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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