Bushong Chapter 4 finished Electricity, Magnetism, and Electromagnetism

what is the primary function of a x-ray imaging system?

to convert electric energy into electromagnetic energy

the electric motor converts electric energy into what?

mechanical energy

the electric range converts electric energy into what?

thermal energy. ex toaster

define electrostatic

the study of stationary electric charges

an object is said to be electrified if it has _______ or ________ electrons

too few or too many

what are the 3 ways electrification can be created?

contact, friction, or induction

what is an example of contact?

touching a metal doorknob after walking across a carpet in winter, you get a shock

what is an example of friction?

when electrons are rubbed off the carpet onto your shoes

what is an example of induction?

when there is a thunderstorm, wind and cloud movement can remove electrons from one cloud and deposit them on another.

define electric ground

one object that is available to accept electric charges from an electrified object, acts like a reservoir. ex earth

where does lightning occur?

occurs between an electrified cloud and the earth. the discharge between clouds that is deposited in another (lightning)

what is the unit of electric charge?

the coulomb (C)

1C is equal to how many electron charges?

1C = 6.3 x 10*18 electron charges

what are the 4 laws of electrostatic?

1. Like charges repel and unlike charges attract each other.

2. Coulomb's law: The electrostatic force between two charges is directly proportional to the product of their quantities and inversely proportional to the square of the distance between them.

3. Electric charge distribution is uniform throughout or on the surface.

4. Electric charge of a conductor Glossary is concentrated along the sharpest curvature of the surface.

what is Coulomb's law?

the electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them.

define electrostatic force

the force of attraction between unlike charges or repulsion between like charges is attributable to the electric filed.

electrostatic charges are concentrated on surfaces of sharpest or smoothest curvature?

sharpest

what is the unit of electric potential?

volt (V)

the higher the voltage, the greater the what?

the greater is the potential to do work

in the US the electric potential in homes and offices is what?

110V

Imaging systems usually require how much electric potential?

220V or higher

the volt is?

potential energy/unit charge or joule/coulomb (1V = 1J/C)

define electric current

when electric potential is applied to objects, like a copper wire, the electrons move along the wire

electrodynamics is the study of what?

the study of electric charges in motion

electric current is always opposite that of electron flow. T/F

True

what is a conductor?

any substance through which electrons flow easily

what are some examples of electric conductors?

metals and water

what is an insulator?

any material that does not allow electron flow

what are some examples of insulators?

glass, clay, and rubber

what is a semiconductor?

a material that under some conditions behaves as an insulator and in other conditions behaves as a conductor. ex silicon and germanium

what is superconductivity?

the property of some materials to exhibit no resistance below a critical temperature. ex niobium and titanium

at room temperature do all materials resist the flow of electricity?

yes

what is an electric circuit?

is a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.

electric current is measured in what?

Amperes (A) 1A = 1C

electron resistance is measured in what?

ohms

what is Ohm's law?

the voltage across the total circuit or any portion of the circuit is equal to the current times the resistance.

what is the function of the resistor in the circuit?

inhibits flow of electrons

what is the function of a battery in the circuit?

provides electric potential

what is the function of the capacitor in the circuit?

momentarily stores electric charge

what is the function of the transformer in the circuit?

increases or decreases voltage by fixed amount (AC only)

what is the function of the diode in the circuit?

allows electrons to flow in only one direction.

rules for series circuits

the total resistance is equal to the sum of the individual resistances.

the current through each circuit element is the same and is equal to the total circuit current.

the sum of the voltages across each circuit element is equal to the total circuit voltage.

rules for a parallel circuit

the sum of the current through each circuit element is equal to the total circuit current.

the voltage across each circuit element is eh same and is equal to the total circuit voltage.

the total resistance is the inverse of the sum of the reciprocals of each individual resistance.

electric field

line of force exerted on charged ions

positive charge

point outwards

negative charge

point downwards

electrostatic force

force of attraction between like charges

electrodynamics

study of electric charges in motion

electrical engineer

works with electric current

physicist

works with electron flow

four states of matter

conductor, insulator, semiconductor,superconductor

conductor

electron flows easily

insulator

doesn't allow electron flow

semiconductor

behaves as insulator or conductor

superconductor

allows electron flow without resistance. Niobium, Titanium

William shockley 1946

demonstrated semiconduction

super conductivity 1911

no resistance within a critical temperature

electric circuit

path of electron flow through a conductor

1V

1J/C

electric resistance

measured in omhs

battery

provides electric potential

capacitor

momentarily stores electric charge

ammeter

measures electric charge

transformer

increase and decrease voltage

rheostat

variable resistor

diode

electron flow in one direction

direct current

electron flow in only one direction

alternating current

electron flows alternately. 60Hz current

wave form

graphic representation of wave

electric power

measured in watts

magnetite

oxide of iron Fe3O4

magnetism

fundamental property of some forms of matter

electron spin

a property created when electron behave as they rotate on its axis

magnetic moment

basis of MRI

bipolar

has two poles

poles

north and south pole

magnetic dipole

small magnet created by electron orbit

magnetic domain

accumulation of atomic magnets with dipoles aligned

magnetic permeability

ability of the material to attract lines of magnetic field

three types of magnet

naturally occuring magnets

permanent magnets

electromagnets

ferromagnetic

it can be strongly magnetized

nonmagnetic

unaffected By magnetic field

soft iron

an excellent temporary magnet

voltaic pile

precursor of modern battery

alessandro volta

contributed on the development of battery

magnetic field strength

Si unit: tesla

older unit: gauss

1T: 10,000G

natural magnet

a magnet that get its magnetism from the earth

magnetic induction

the process of Making ferromagnetic material magnetic

closed core transformer

a square core of ferromagnetic materials built up of laminated layers of iron. It reduces energy loss caused By Eddy current

source of electromagnetic force

any device that converts some form of energy directly into electric energy

Hans oersted

he demonstrated that electricity can be used to generate magnetic fields

electromagnetic devices

electric motor, electric generator and transformer

magnetic lines of induction

the imaginary magnetic field lines

solenoid

a coil of wire

electromagnetic

a coil or wire wrapped around an iron core that intensified the magnetic field

Eddy Current

a current that opposes the magnetic field that induced it, creating a loss of transformer efficiency.

step up transformer

turns ratio greater than 1

primary side: low voltage, high current

shell-type transformer

it confines more of magnet field lines of primary winding.

Advantage: more efficient than closed core transformer.

modern battery

carbon rod (+) and zinc cylindrical can (-)

faradays law

the first law of electromagnetic