Quiz 2 Flashcards
What is an electromagnet?
A non magnetic material that takes on the characteristics of a magnet whenever electrical current is passed through
Important date to remember?
Hans Christian Oersted, 1819
Left hand rule?
Point the thumb in the direction of electron flow and the fingers will wrap in the orientation of flow
Why are the lines of flux of a single conductor not useful?
They have no polarity and are too weak to be useful.
What are the two ways flux strength can be increased?
Increasing the current through the conductor, increasing the density of the lines of flux.
Flux density can be increased in what two ways?
By wrapping conductor in a coil, inserting a highly permeable core
what are the advantages to forming a coil?
The strength of the flux is increased , and gives the flux polarity
Left hand rule for coils?
Wrap the fingers of the left hand around the coil in the direction of electron flow, the thumb will point to the North Pole
In what two ways can the polarity of a coil be reversed?
Reverse the current flow through the conductor, reverse the direction of the wraps.
Measurements of flux?
Gilbert and amp turn
What is the advantage to having an electromagnet?
It has the characteristics of a natural magnet which can be controlled, both strength and polarity
Uses for electromagnets?
Relays, solenoids, generators, alternators, motors
Difference between a relay and a solenoid?
Relay uses a non movable core
What is a relay/solenoid?
An electrical switch which is operated by an electromagnet
What is the purpose of a relay?
To use a small amount of current to control a large amount of current
What is a generator/alternator?
A device which uses an electromagnet to generate electricity
Difference between a generator and an alternator?
In a generator the electromagnet does not spin
What is a motor?
A device in which two electromagnets with fields that repel each other and cause one of them to spin
What are the sources of electricity?
Magnetism, chemical, heat, pressure, light.
Example of magnetic power?
Alternator, generator
Example of chemical power?
Batteries
Example of thermal power?
Thermocouples
Example of pressure power?
Record needle
Example of light power?
Solar panels
What is the definition of a complete circuit?
An electrical circuit where there is a complete path from the source, to the load, and back to the source.
What is a source?
The part of the circuit that provides the potential for electron transfer.
What is a conductor?
The path by which electrons flow from the source, to the load , and back to the source.
What is the major consideration for choosing a material for a conductor?
Weight versus resistance