ME6 - Electromagnetism Flashcards Preview

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Flashcards in ME6 - Electromagnetism Deck (14):

What does a current carrying wire create?

A magnetic field


The larger the electric current...

The stronger the magnetic field


What does the direction of the magnetic field depend on?

The direction of the current


What magnetic field is around a straight wire?

A field made of of concentric circles with the wire in the centre


What is the magnetic field around a flat circular coil like?

- Around the centre of the flat circular coil of wire it is similar to that of a bar magnet

- Around the coil there are concentric ellipses (stretched circles)


Describe the magnetic field around a solenoid like?

- Strong and uniform inside current carrying solenoid

- Outside the coil it is like a bar magnet (ends of solenoid act as a north and south pole making an electromagnet)


What can magnetic materials either be?

Hard or soft


Why are magnetic materials like iron considered soft?

It looses its induced magnetism quickly (temporary magnet)


Why are magnetic materials like steel considered hard?

The magnetism is kept permanently (permeant magnet)


Why is iron used in transformers?

Because of its properties - it needs to magnetise and demagnetise 50 times per second


How can you increase the strength of a magnetic field around a solenoid?

Add soft iron core


Why are electromagnets far more useful than permanent magnets?

- Turn on and off
- Change the magnetic field strength
- Change the shape of the magnet


What is an example of a use of electromagnets?

Lifting metal objects and the electric bell


Describe the construction of a electromagnet

Current carrying wire wrapped into coil, wrapped around an iron core