Introduction
 

Electrical energy is transferred whenever electric current flows through a circuit. Understanding how energy and power are related is essential for analysing electrical devices, calculating energy consumption and explaining how efficiently electrical systems operate. This topic builds on the concepts of current, potential difference and resistance introduced earlier in the Electricity section.
 

In this topic, students learn how to calculate electrical energy and power using a range of equations, understand the relationships between current, voltage and resistance, and apply these principles to practical electrical circuits.
 

AQA A Level Physics Specification: 3.2.4.3 Energy and Power
 

What You Need to Know
 

• Define electrical power as the rate of energy transfer.

• Calculate electrical energy transferred using:

  • (E = Pt)

  • (E = VIt)

• Calculate electrical power using:

  • (P = VI)

  • (P = I^2R)

  • (P = \dfrac{V^2}{R})

• Understand the relationship between energy, power and time.

• Apply power equations to solve practical circuit problems.

• Calculate the energy transferred and the cost of using electrical appliances.

• Understand how energy is dissipated as thermal energy in electrical components.

• Select and apply the most appropriate equation when solving examination questions.
   

Downloadable Topic Pack
 

Energy & Power Topic Pack Exam Questions and Answers
 

Related Topics

• IV Characteristics and Electricity Basics

• Resistivity & Superconductors

• EMF and Internal Resistance

• Potential Divider

• Electric Field Strength