Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
|
Motor |
Converse electrical energy to mechanical energy 1. Components: same as generator 2 operation: - I (current) passes through the coil - magnetic field of the I (current) interacts with permanent magnetic field causing coil to move |
|
|
Electric potential |
Any device that converts some form of energy directly into electrical energy is said to be a source of electric potential. electric potential is measured in units of joule per coulomb , or volt. |
|
|
Magnetic fields |
Any charge in motion and there is a magnetic field A charge at rest produces no magnetic field. electrons that flow through wire produce a magnetic field about that wire. the magnetic field is represented by imaginary lines that form concentric circles center on the wire |
|
|
Solenoid- |
helix with a current A helix is just a coil of wire. And coil of wire is called a solenoid The magnetic fields of a solenoid is concentrate through the center of the coil Magnetic field can be intensified further by wrapping the coil wire around the ferromagnetic materials such as iron. iron core intensifies the magnetic field. in this case, almost all the magnetic field lines are concentrated inside the iron core, escaping only near the end of the coil. this type of device is called an electromagnet |
|
|
Electromagnet |
And electromagnet is a current carrying wire wrapped around an iron core which intensifies the Induced magnetic field Solenoid with an iron core Ferromagnetic material increases the magnetic strength |
|
|
Electromagnetic induction |
An electric current is induced in a circuit if some part of that circuit is in a changing magnetic field Therefore, to induce a current with the use of a magnetic field, the magnetic field cannot be constant but must be changing |
|
|
Faradays law |
First law of electromagnetism
The magnitude of the induced current depends on four factors 1. The strength of the magnetic fields(magnets) - increase magnet strength = increase current 2. The velocity of the magnetic fields as it moves past the conductor (speed of motion) - increase speed= increase current 3. The angel of the conductor to the magnetic field (direction of motion) - 90° to magnetic fields = strongest current 4. The number of turns in the conductor (shape of the conductor) - the more coils the stringer the current |
|
|
What induces an electric current |
Verying magnetic field intensity induces an electric current |
|
|
What is an induction motor |
The type of motor use with an xray tube is an induction motor. In this type of motor the rotating rotor is a shaft made of bars of copper and soft Iron fabricated into one mass; however the external magnetic field is supplied by several fixed electromagnets call stators |
|
|
Transformer |
A transformer changes the intensity of alternating voltage and current A transformer will operate only with a changing electric current (AC) we need movement!! |
|
|
Transformer law |
(Vs/Vp) = ( Ns/Np) The quantity of Ns/ Np is known as the turns ratio of the transformer |
|
|
Step-up transformer |
A transformer with a turns ratio greater than one as a step up transformer because of voltage is increased or stepped up from the primary side to the secondary side |
|
|
Step-down transformer |
When I turn ratio is less than one the transformer is a step down transformer |
|
|
Magnetic field direction— produced by I(current) |
•right thumb rule - indicates the direction of the magnetic field around that wire. |
|
|
Mutual induction |
Magnetic field induceis a current in a nearby helix |
|
|
Generator |
Converts mechanical energy to electrical energy 1. Wire coil between magnetic poles 2. Operation - Call is mechanically turned within field (armature) -As coil moves it cuts through field -current induced |
|
|
Slip rings / contact / brush |
Back (Definition) |
|
|
AC generator operation 69 Hz frequency, 120 alterations (impulses) |
Back (Definition) |
|
|
Motor |
Converse electrical energy to mechanical energy 1. Components: same as generator 2 operation: - I (current) passes through the coil - magnetic field of the I (current) interacts with permanent magnetic field causing coil to move |
|
|
Power losses |
•Copper •hysteresis - rearranging magnetic domains •eddy current -swirling currents in the core -minimized by lamination of plates |
|
|
How much amperage does it take to boil off electrons of a coil of wire |
3-6 amps |
|
|
Thermionic emission |
To “boil off” electrons |
|
|
Synchronous motor |
Coil rotates at same frequency as current 60 Hz. Used in timing circuits in older machines |
|
|
Mutual induction |
Magnetic field induceis a current in a nearby helix used in step up and down transformer |
|
|
Closed-core transformer |
Back (Definition) |
|
|
Self induction |
One could inducing another current on itself |
|
|
AC generator operation 60 Hz frequency, 120 alterations (impulses) |
Back (Definition) |
|
|
Autotransformer |
Operates on the principle of self induction Variable transformer Submerged in oil to reduce shock It consist of an iron core with only one winding of wire about it. this single winding acts as both the primary and the secondary winding. connections are made at different points on the coil for both the primary and the secondary sides The autotransformer has one winding and varies both voltage and current. |
|
|
Shell-type transformer |
Most efficient This type of transformer confines even more of the magnetic field lines of the primary windings because the secondary is wrapped around it and there are essentially two close cores. this type is more efficient and then the closed-core transformer. Most currently use transformers are shell type. |
|
|
Who developed the battery? |
Alessandro Volta Developed the battery as a source of electric potential energy and prompted additional investigations of electric and magnetic fields |
|
|
Who discovered the electric currents produces a magnetic field? |
Hans Oersted |
|
|
Who discovered that Current was produced in the presence of a changing magnetic field? |
Michael Faraday |
|
|
Magnetic field— produced be I(current) |
•right thumb rule - indicates the direction of the magnetic field around that wire. |
|
|
Lenz law- second law of electromagnetism |
The induced current flows in the opposite direction of the applied current back electro-motive force EMF or principle of self induction |
|
|
Self induction |
The induction of an opposing electromagnetic field in a single coil by its own changing magnetic field |
|
|
AC generator operation 60 Hz frequency, 120 alterations (impulses) |
Back (Definition) |
|
|
Mutual induction |
Magnetic field induceis a current in a nearby helix |
