| A | B |
|---|
| potential difference | change in total energy divided by total charge; measured in volts; when potnetial difference stays the same, current decreases as resistance increases |
| diffraction | bending of waves--light or sound--passing trhorugh openings, around corners |
| electro magnet | magnet produced by passing electric current through a coil of wire wound around a core |
| conductor | material that allows electric current to freely pass from place to place; conductors attracted to both + and - charges; copper, gold, silver |
| cicuit | any complete pathway through which electrical current passes; 3 parts required: source of potential difference, a conducting path , resistance |
| electric generator | produces electricity for home and business by inducing currents through rotating a coil with a magnetic field |
| insulator | material that does not allow electrical current to flow freely (paper,plastic wood, glass) insulators help to aloow ectricity to flow safely from one point to another |
| electrical charge | concetration of electricity |
| unlike charges | dissimilar electric charges that attract each other |
| resistance | property of materials indicating how much energy is changed to thermal energy and light as an electric charge passes through them |
| like charges | similar electrical charges that repel each other; eg, when 2 glass rods are charged by rubbing them agains silk, when they a re borugh together they will repel each other |
| current | rate at which electricl current flows past a point in a circuit in a specific period of time; can be measured by ammeter; current is equal to potential difference dived by resistnace V/R=I |
| radioactivity | decay or breaking apart pf unstable elements such as uranium resulting in a release of high energy particles; radiaiton can be separted into alpha, beta and gamme rays |
| Granville T. Woods | inventor who applied elctro magnets to telephone transmitters |
| electric motor | motor that used electromagnet to change electric energy into mechanic energy allowing machine to work |
| induced current | electric current produced by using a magnet;results when a magnetic field is changed in a coil; field can be changed by moving coil or magnet |
| induced magnetism | magentism that occurs only in the presence of a magnetic field; when the magnetizes object is removed from the magnetic field, its poles disappear |
| loudspeaker | changes variations in electric current into sound waves in radios and speakers |
| magnetic field | 3 dimensional region where magnetic forces act |
| magnetic poles | in a bar magnet the poles that point north and south; 2 north seeking poles repel each other; 2 south seeking poles repel each other |
| transformer | regulates amount of electricity transmitted by power company to assure the corret level is delivered |
| electro magnetic spectrum | the entire range of electromagnetic waves from low frequncy radiowaves to high frequency gamma rays |
| electromagnetic wave | transverse waves that do not require a medium thorugh which to travel and which are produced by an oscillating charge; moves at constant speed so its wavelength is proportional to to its frequency; examples include micorwaves, visible light, xrays |
| thin film | diffract grading |
| frequency of electromagnetic wave | is determined by the speed divided by teh wavelengthf light |
