material science: ceramics
why does the tungsten filament give off light?
the electrons generate friction closely packed. when the electric current follows the metal pathway through a flamed light bulb, a tremendous amount of resistance is encountered as the electrons make their way through the very thin wire filament.
current: I
the flow of charges through a wire or any conductor, measured in amperes.
amount of resistance determines
the flow of electrons, amperes. which causes changes in the amount of heat and light produced.
when you lit the lantern mantle where did the metal go? remember matter cannot be created or destroyed.
the metal turned into gas.
resistance: R
the tendency of a material to oppose the flow of electrons, measured in OHMS
watt: W amount of energy per second, j/s
ex: a 100 W bulb produces more energy than 975 W bulb.
incandescent
glowing with heat, like the filament does.
less resistance=
greater flow of electrons= more heat= more light, watts.
incandescence
growing with heat.
how is the thickness of the filament related to the resistance and the wattage of the bulb?
it would have more resistance because it has less space, the wattage would be less sense the electrons aren't moving out the filament.
resistance
opposition to flow of electrons. measured in OHMS- affected by type of material, length of wire, thickness of wire.
voltage differences: E
push that causes electrical current to flow through a conductor, measured in volts, V.
what category of material did the tungsten metal change into when it was plugged into electricity while exposed to air?
the tungsten metal changes to ceramics. it is the process by which a solid is converted directly into a gas without first passing through a liquid phase.
what is the purpose of the light bulb envelope?
to keep oxygen out.
what were some characteristics of the glass envelope?
it was oblique, lustrous, brittle, silver bottom/ white top.
detailed description about the aluminum wire.
flexible, lustrous, work harden, low melting point.
what gasses are used inside a light bulb and why are those particular ones chosen?
all noble gasses because they don't want to react to anything sense they already have 8 electrons.
nichrome
alloy of 80% nickel and 20 % chromium. used in appliances such as toasters and hair dryers.
power: P
amount of energy transferred in a certain time, measured a watts, W.
why is tungsten used as the filament in a light bulb instead of another metal?
atoms are still sealed inside with no where else to go. if you were to examine a burned out light bulb, you'll see a tungsten deposits on their interior surface of the glass. edison found that most filaments with oxygen involved cause the hot material to break rapidly. this is why we use the tungsten as a filament instead of either metals.
what causes a light bulb to fail?
because of the it sublimates, which means it the electrons leave the wire turning into gas.
describe the property changes that occurred in the tungsten filament when it was heated while exposed to oxygen in the air. what was this reaction called? what unit does it relate to from the first semester?
when the tungsten filament was heated while exposed to oxygen it burnt out and turned into a ceramic. this is called oxidation. its from our metal unit where we talked about corrosion.
why is there a gas inside of a light bulb instead of a vacuum?
without a gas inside of a light bulb, exerting pressure on the filament, the rate of sublimation increases, the vacuum creates this problem.
do light bulbs actually "burn out" when they quit working?
yes they do because they stop producing like light. although the electrons are there, there is no heat to make them have energy.