Physics » Magnetism and Faraday's Law » Electrical Machines - Generators And Motors

# Introducing Electrodynamics

## Electrodynamics: Introduction

In the previous lessons, you learnt how a magnetic field is generated around a current-carrying conductor. You also learnt how a current is generated in a conductor that moves in a magnetic field or in a stationary conductor in a changing magnetic field. The next set of lessons describe how conductors moving in a magnetic field are applied in the real-world.

Today, currents induced by magnetic fields are essential to our technological society. The ubiquitous generator—found in automobiles, on bicycles, in nuclear power plants, and so on—uses magnetism to generate current. Other devices that use magnetism to induce currents include pickup coils in electric guitars, transformers of every size, certain microphones, airport security gates, and damping mechanisms on sensitive chemical balances. Not so familiar perhaps, but important nevertheless, is that the behavior of AC circuits depends strongly on the effect of magnetic fields on currents.

### Key Objectives

Electrical machines – generators and motors:

• State the difference between generators and motors.
• Definition of Farady’s Law.
• Using Faraday’s Law for explanations.
• Definition of a generator
• Explaining the principle of an AC and DC generator using words and pictures.
• Explaining the difference between AC and DC generators.
• Explains what happens when a current carrying coil is placed in a magnetic field.
• Explaining the principle of an electric motor using word and pictures.
• Definition of Lorent Force.
• Examples of AC and DC generators and the use of motors.

Alternating current:

• Explaining advantages of alternating current.
• Write different expressions.
• Definition of the root mean square values and explains why they are useful.
• Calculations done on the average power.
• Drawing of graphs.
• Solve different kinds of problems using alternating current.