Electricity, Magnetism, & Electrical Power

4 fundamental physical forces

Electromagnetism, gravitation, & 2 forced holding atomic nuclei together

Inherent properties of matter

electromagnetism & gravitation

The area around a charge does not affect other charged bodies

True

Any charged particle whether moving or stationary, generates a

Field of Force

Electrical Force =

constant (Charge of A) (Charge of B) / (distance between the charges)^2

Coulomb

SI unit of charge; equals the charge carried by 6.24 x 10^18 electrons (MKS)

Statcoulomb

smaller unit of charge (CGS)

Electrical Field

A series of pushes in the form of energy

Electrons in ______ carry current

metals

Ions in ________ carry current

solution

Volts

unit of measurement for electrical potential that is measured with respect to some other point (MKS)

Statvolts

CGS measurement for electrical potential.

Energy (Joule)=

Electrical Potential (Volt)x charge (Coulomb)

Voltage tells us

nothing about the movement of the current, it is a description of the electrical potential of a system

Amperes

the unit for measuring current (MKS), the movement of one coulomb of charge past a given point in a second

Stat Amp

CGS unit for current

Electrical resistors

inhibit the flow of current and cause heat build up

Ohm

MKS unit for resistance

statohm

CGS unit for resistance

Superconductors

are metals cooled to extremely low temperatures (-270 degrees Celsius) causing the resistance to decrease sharply; caused an easy flow of electrons

Ohm's Law

the voltage drop across a resitor is equal to the current x resitance or V=IR

Electrical & Mechanical ENERGY

can be converted to heat or work

Heat

Generated when an electrical current passes through a resistor & Mechanical WORK is generated when an electrical current is passed through coils of an electrical motor

Power

Energy / Time, current x voltage, push x amount being pushed

Watt = _____________

1 Joule/second

Among the wires that come from an outside pole to your house, ___ are hot wired with ___. The third wire is the ______ & is maintained at ____ volts (connected to ground)

Two, AC, ground, zero

Wall sockets operate at

110 volts

Wall sockets are wired with one ___ wire and one _____ wire

hot & ground

Some large pieces of equipment require ___ _____ & need both ___ and ______ wire

220 volts, hot, & ground

You buy ______ to push electrons around from power companies not the ________ themselves

Energy & electrons

Series circuit

The power output of any appliance is dependent upon the other resistors in the line & changes drastically

Adding more resistors to a series circuit

total current decreases

As you add more resistors to a Parallel circuit

total current increases

Fuse

A device with a metal strip making an electrical connection between 2 points in a wire; it keeps the wire from becoming too hot & causing a fire

Good power tools have _____ wires leading from them

Three

How are electric circuits used?

In counting, switching, sending, & amplifying devices

Amplification

Accomplished through the use of vacuum tubes or transistors

Triode Vacuum Tube

A vacuum tube with 3 electrodes: Cathode, grid, & anode

Semiconductor device

Made from materials that are neither a good conductor nor a good insulator

Only some objects possess intrinsic ________ ________; the most common is ____

Magnetic behavior & iron

When a bar magnet is cut in half you get

2 similar magnets

Magnetism arises out of the arrangement of ________ in an iron atom & is ________ to that element

Electrons & intrinsic

Domains

Small bundles of atoms sticking together in a magnetic alignment

Domains in nonmagnetic substances point

In all directions

if a solid is subjugated to a strong outside magnetic field, most of the domains will line up with the external field and the solid becomes

A magnet

bar magnets do not last forever. The ______ will jiggle back into a ______ __________

Domain & random orientation

Oersted

Completed experiments with magnetism and its relationship to electricity. He also discovered that the lines of a magnetic field generated by an electric current flowing through a wire form concentric circles about the wire. He also discovered that electrical energy can be converted to mechanical work.

The field of a magnet held near a wire carrying a current will interact with the field

generated by current

Stationary electric field

does not interact with stationary magnetic fields and no force is generated if the electrons move in line with the magnetic field.

An electromotive force is generated only if a charged particle moves ______ the magnetic field

Across

the magnitude of an electromotive force is proportional to the ________ __ ___ ________ _____ & to the ______ __ _______ passing through it.

Strength of the magnetic field & amount of current

Henry and Faraday

independently produced in electric current by moving a magnet up and down through a coil of wire. They also discovered that mechanical energy can induce electrical current.

Electromagnetic Induction

generating a current by either moving a magnet perpendicular to a wire or by moving the wire perpendicular to the magnetic field

The discoveries of Henry and Faraday paved the way for

Electromagnets, electric motors, electric generators.

Permanent magnets are preferred over electromagnets

False

Coiling a wire in the shape of a loop produces a field the same shape as a

Bar magnetic field

In an electromagnet, the strength of the field is directly proportional to the

current

Electromagnets

are constructed by coiling a wire around iron and connecting the wire coils to a direct current source. They are more versatile than permanent magnets

Electric motors

were first constructed by Oersted

Electric motors have only one moving part which is

A Central shaft containing wire coils

In motors, a rotating loop rubs against stationary contacts. this causes the _______ _____ __ _________ to wear out after a while and must be replaced

Rubbing parts or bushings

When a motor is started, a spinning coil does mechanical work and generates electricity. Therefore, every motor is a

generator

Electromotive force

the voltage resisting the flow of electrons into a motor

Motor effect

the force in a generator opposing an applied mechanical force.

Transformer

Device that changes the voltage of a circuit, but does not itself produce electric power

Name three ways to induce current:

Moving a magnet back and forth across a wire; moving a wire through a magnetic field; placing an electro magnet perpendicular to a wire maintaining both in a fixed position and vary the strength of the electromagnet by varying the current through it

Naturally occurring magnetic fields common through universe; maybe observed using a

compass

Most texts suggest that the earth's core is ______; and this interior acts as a giant _________ to provide ___________.

Matter, generator, and electricity.

Earth's magnetic field has _______ several times during geological history.

shifted

Magnetic field is a __________ _____ around the planet.

Protective field

The Earth's magnetic field protects from

Cosmic rays, highly energized, fast moving charged particles

These particles (Hydrogen and Helium) may

Damage living cells and alter genetic information in reproductive organs