A fundamental force in nature that gives some forms of matter the ability to attract other forms of matter, such as iron
In 1600, English scientist ____ ____ confirmed earlier observations regarding magnetic poles and concluded that the Earth was a magnet.
___ ___ ___ - created when electrons orbits the nucleus in a closed loop
Orbital magnetic moment
___ ___ ___ - created when electrons spin on their axis (protons in the nucleus also exhibit this property - basis of MRI)
Spin magnetic moment
The small magnet created by an electron in orbit called a?
Groups of many atoms with their dipoles aligned created a?
Magnetic fields are referred to in terms of lines of force or?
Lines of Flux
The number & concentration of the lines of flux in an area determines the strength of the magnetic field and magnet called?
the SI unit for measuring field strength (flux density) is ___?
the Tesla (T)
Serbian-American inventor, electrical engineer, mechanical engineer, physicist, and futurist who is best known for describing rotating magnetic fields in 1882 & later developing AC electrical systems.
The 3 Magnetic Classifications are?
1. Natural - those created within the earth
2. Artificial permanent - those manufactured out of metal alloys
3. Electromagnets - temporary magnets produced by moving electric current
Artificial Permanent Magnet
What is ALNICO?
an alloy of Aluminum, Nickel, and Cobalt
What 3 things make up the Laws of Magnetism.
- 1. Repulsion-attraction
- - Like poles repel; unlike poles attract
- 2. Inverse Square Law
- -The force between 2 magnetic fields is directly proportional to the product of their magnitudes & inversely proportional to the square of the distance between them.
- 3. Magnetic Poles
- - Every magnet has 2 poles, North and South.
- - If you divide a magnet it creates 2 magnets - each with a North and South pole
____ - the ease in which a material can be magnetized
___ - the ability of a material to stay magnetized
The 4 Magnetic Classifications of Materials are?
- 1. Ferromagnetic - materials that are strongly attracted to magnets and magnetic fields
- Ex: Iron, nickel, and cobalt
- 2. Nonmagnetic - materials not affected by magnets or magnetic fields
- Ex: Wood, glass, rubber, and plastics
- 3. Paramagnetic - materials weakly attracted to magnets and magnetic fields.
- Ex: Platinum, aluminum, and magnesium
- 4. Diamagnetic - materials weakly repelled by magnets and magnetic fields.
- Ex: copper, silver, lead, and gold.
Electricity & Magnetism can be thought as different aspects of the same force: _____
Danish chemist & physicist who first demonstrated in 1820 that electric currents created magnetic fields. Experiment with an electrical wire and a compass.
What was the Right-Hand Rule, and who created it?
The right-hand rule describes the direction of the current and magnetic fields along a conducting wire.
This rule was created by English scientist John Fleming)
When a conducting wire is looped and electric current passed through it, a _____ is created.
A _____ is a solenoid with a ferromagnetic material (such as an iron bar) added to the center. This increased the magnetic strength further.
The strength of a solenoid or electromagnet depends on what 3 things?
1. The number of loops (turns) of wire
2. The strength of the electric current passed through it
3. The permeability of the core
- Solenoids & electromagnets are used for detents and other locks on radiographic equipment.
____ ____ is the production of an electric current in a conductor by a changing magnetic field.
English scientist who described the principles of electromagnetic induction in 1831.
Faraday's Law: The 4 factors that regulate the strength of induced current are?
1. The strength of the magnetic field
2. The speed of motion between the line of flux and the conductor
3. The angle between the magnetic lines of force and the conductor
4. The number of turns in the conducting coil
Induction of current in a secondary coil by applying a varied current through a primary coil - is an example of what?
Induction of an opposing voltage in a single coil by its own changing magnetic field: is an example of?
____ - Devices that convert mechanical energy into electrical energy through principles of electromagnetic induction.
___ - Devices that convert electrical energy into mechanical energy (motion)
Rotor - bars of copper around an iron core
Stator - electromagnets arranged around the rotor
together make up a type of ____ ____
The 3 factors of controlling Electricity are?
____ - Devices used to change the magnitude of voltage in an AC circuit
___ ___ transformers convert lower AC voltages into higher AC voltage
- - has more turns in the secondary coil than is found in the primary coil
___ ___ transformers convert higher AC voltages into lower AC voltage
- - has less turns in the secondary coil than is found in the primary coil
____ ____ - voltage change across a transformer is directly proportional to the number of turns
Name the 4 types of Transformer configurations.
1. Air Core - a simple transformer
4. Shell type
____ - A variable transformer that can act as a step-up or a step-down transformer.
The 3 types of transformers in x-ray machines are?
1. Autotransformer - used to vary the incoming line voltage sent to the high-voltage step-up transformer
2. Step-up transformer - used to raise the incoming line voltage to kilovoltage (kV) needed for x-ray production
3. Step-down transformer - used to decrease the incoming line voltage needed to heat the x-ray filaments and produce electrons (filament circuit/mA)
____ - Devices used to accumulate & store electric charges
____ - The process of changing AC into pulsating DC
Most common type of rectifier in x-ray machines: ?
solid-state semiconductor diodes
___ ___: the negative portion of the AC cycle is suppressed by the flow of electrons
___ ___: the negative portion of the AC cycle is changed to positive