Ch. 2 Electromagnetic Radiation, Magnetism, and Electrostatics

Ace your homework & exams now with Quizwiz!

1 Hz = how many cycles per second?

1 Hz = 1 cycle per second

What are the 4 types of magnetic materials?

1. Ferromagnetic 2. Paramagnetic 3. Diamagnetic 4. Nonmagnetic

Laws of Magnetism

1. Magnetic Poles 2. Repulsion-Attraction 3. Inverse Square Law

Electrostatic laws

1. Repulsion-Attraction law 2. Coulomb's law 3. Distribution law 4. Concentration law 5. Movement law

Electromagnetic radiation characteristics

1. Velocity 2. Frequency 3. Period 4. Wavelength 5. Amplitude 6. Energy 7. Intensity

3 methods of electrification?

1. friction 2. contact 3. induction

Electromagnetic spectrum in order from longest wavelength to shortest wavelength, low energy to high energy, and low frequency to high frequency

1. radio 2. radar 3. infrared 4. visible light 5. ultra violet light 6. xray 7. gamma 8. cosmic

A wave with a frequency of 2 cycles per second has a period of what?

1/2 second - one wave is completed in 1/2 second

Planck's constant

4.15 x 10 ^ -15 eVs (electron volts per second)

How many electron charges = 1 coulomb?

6.3 x 10 ^18 electron charges = 1 coulomb

In the US electricity has what frequency?

60 Hz

How many cycles per second is 60 Hz?

60 cycles per second

What is the formula that demonstrates the relationship between energy and frequency?

E = hf - E= photon energy in electron volts (eV) - h= Planck's constant - f= frequency

Inverse square law formula?

I1/ I2 = D2^2/D1^2 -I1= old intensity -I2= new intensity -D1= old distance -D2 = new distance

When a nonmagnetized material is introduced into a magnetic field, the material is magnetized, and then is removed from the magnetic field, and the material is no longer magnetized, what is this called?

Magnetic induction - works with any ferromagnetic material

What is a temporary opposite charge?

When electrification by induction occurs and the electrons will return to their original positions when the charged object is withdrawn

What surrounds a magnet or moving electric current?

a magnetic field (flux lines); all magnets are surrounded by fields

When a charged particle is in motion, what is created?

a magnetic force field

When electromagnetic radiation acts as a particle (not a wave) it is called what?

a photon or quanta

Magnetism

ability of a lodestone or magnetic material to attract iron, nickel, or cobalt

Why is every magnet bipolar?

all have a north and a south pole, even if they are broken, each piece will have a north and south pole

Paramagnetic materials

aluminum, platinum, gadolinium (MRI contrast)

The wave is demonstrated with what formula?

c = f (lambda) -c=velocity or speed of light -f= frequency -lambda= wavelength

Diamagnetic materials

copper, beryllium, bismuth, lead, and water

What is the unit of electric charge?

coulomb

Energy and frequency are _____ proportional

directly proportional

Nonmagnetic

do not react with magnetic fields

Electromagnetic radiation consists of what 2 simultaneous waves?

electric and magnetic waves at 90 degrees to each other

Concentration law

electric charges concentrate on the sharpest curvature of a conductor -they then discharge to an area of low concentration in an attempt to equalize -electrical potential

Distribution law

electric charges reside on the external surface of a conductor (like a wire) so they can stay as far away from each other as possible (repulsion-attraction law) leaving the inside uncharged

The entire band of electromagnetic energies is called what?

electromagnetic spectrum

Spin magnetic moment

electrons spinning on its axis and also spinning in its orbit (like earth)

Ionizing radiation is described as what?

energy

Magnetic Poles Law

every magnet has a north and a south pole

If the distance from the x-ray source is doubled, the intensity decreases by a factor of what?

factor of 4

Radio waves are described by what?

frequency

What is the unit of magnetism?

gauss (G) and tesla (T) -1 tesla = 10,000 gauss

Infrared radiation

has shorter wavelengths and higher energy than radar and microwaves, can heat nearby objects like a toaster

Radar and Microwaves

have shorter wavelengths and higher energy than radio waves, used in ovens, by law enforcement, and in microwave ovens

What is the unit of measurement for frequency?

hertz (Hz) - 1 Hz = 1 cycle/1 second

Velocity

how fast the radiation moves - CONSTANT (c)

Frequency

how many cycles per second are in the wave; also called rate of rise and fall (number of peaks or valleys in each second)

Where is the magnetic south pole located?

in the north pole

Where is the magnetic north pole located?

in the south pole

Wavelength and energy are ______ proportional

inversely proportional

Friction

involves the removal of electrons from one object by rubbing it with another object (balloon)

Ferromagnetic materials

iron, cobalt, nickel

What does heat do to a ferromagnetic material?

it destroys its magnetism because it rearranges the domains to a random orientation, loosing its permanent magnetism

If frequency is doubled what happens to the wavelength?

it is halved

What is wavelength represented by?

lambda

Repulsion-Attraction Law

like poles repel and opposites attract

Repulsion - Attraction law

like repels like and opposites attract

Other names for magnetic field?

lines of force, lines of flux, force fields

Radio waves

long wavelength low energy radiation waves, used in MRI, wavelengths very very long (football field)

Each atom acts as a very small magnet called what?

magnetic dipole

A group of magnetic dipoles aligned in the same direction is called what?

magnetic domains

Do paramagnetic materials retain magnetism after the magnetic field is removed?

no - so they cannot be permanent magnets

Electromagnetic radiation has what charge and what mass?

no charge and no mass

Contact

occurs when 2 objects touch, allowing electrons to move from one object to another; goes from charged to uncharged or area of high concentration of electrons to low concentration of electrons

Electrification

occurs when electrons are added or subtracted from an object (ionization)

Movement law

only negative charges move along solid conductors -protons are stuck in the nucleus

What happens to the domains in paramagnetic materials when they are placed in a magnetic field?

only some align in the same direction

In which direction does the magnetic forcefield move compared to the charged particle?

perpendicular to the particle

Induction

process of electrical fields acting upon one another without making contact if they are in close proximity and the charge is strong enough

How are the domains oriented when a ferromagnetic material is in a nonmagnetized state?

randomly oriented

Ferromagnetic

react strongly with magnets or in a magnetic field

Visible light

selectively activates cells in the eye, red has the longest wavelength and blue and violet have the highest energy and the shortest wavelengths in the visible spectrum

Electromagnetic radiation with shorter wavelengths has what kind of energy, frequency, and penetration?

shorter wavelengths have higher energy, higher frequency, and more penetration than longer wavelengths

In what waveform do electromagnetic waves move in?

sinusoidal (sine) waves as photons or quanta

Magnetic domains

small groups of atoms that make up magnetic material by aligning in the same direction (they act like tiny magnets inside the material like iron, cobalt, and nickel); they exhibit the magnetic field

What is the unit of measurement for velocity?

speed of light 3 x 10 ^8 meters per second (m/s) or 186,000 miles per second (mi/s)

All electromagnetic radiation travels at what speed?

speed of light 3 x 10 ^8 meters/second or 186,000 miles/second

Another name for stationary charges?

static electricity

All waves have what velocity?

the SAME velocity

Energy

the amount of energy in the wave

As the energy of the wave increases what happens to the amplitude?

the amplitude increases or the height of the wave increases

Wavelength

the distance between corresponding parts of the wave (from peak to peak or valley to valley)

Electric field

the electrical force exerted on a charge; around all electrical charges toward negative and away from positive charges; a charge object has a force field surrounding it, that is the electric field

Coulomb's law

the electrostatic force between 2 charges is inversely proportional to the square of the distance between them (Inverse square law)

Intensity

the flux of the energy; energy flow per second

Inverse square law

the intensity of something is inversely proportional to the square of the distance from the source

Inverse Square Law for laws of magnetism

the magnetic force between two magnetic fields is inversely proportional to the square of the distance between them

Amplitude

the magnitude of the wave (how high the peak goes from 0 or from the line of propagation in either direction)

Electrostatics

the study of stationary or resting electric charges

Period

the time for one complete cycle

Why are nonmagnetic materials not attracted to magnets?

there are an equal number of dipoles spinning in both directions

When a ferromagnetic material is placed in a magnetic field what happens to the domains?

they are aligned

Wavelength and frequency have what kind of relationship?

they are inversely related - if wavelength goes up frequency goes down

After the magnetic field is removed from a ferromagnetic material after being introduced, what happens to the domains?

they remain aligned forming a permanent magnet

Ultraviolet light

used in labs to destroy airborne bacteria and can cause sunburn

X-rays and Gamma rays

very short wavelengths, high energy, high frequency radiation, measured in kilo electron volts (keV), used for x-ray and radiation therapy

Electromagnetic radiation may appear in what forms?

visible light, x-rays, infrared, or radio waves

What is the unit of electrical potential?

volts

What is intensity measured in?

watts/cm^2

Light is described by what?

wavelength

Paramagnetic

weakly attracted to magnetic fields

Diamagnetic

weakly repelled by a magnet

Nonmagnetic materials

wood, glass, rubber, and plastics

The earth has what kind of potential? Why?

zero or ground potential because it is neutral


Related study sets

Ch. 14 ~ Risk of infectious and Communicable diseases ((exam 3))

View Set

Culinary Arts 1 Midterm Study Guide

View Set

State exam simulator- weighted exam

View Set

Chapter 4: Retirement and Other Insurance Concepts

View Set