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How hot does a filament light bulb get?

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Hot, really hot. Typically in the range of about 2000C to 2500C (3600F - 4500F). It would be pretty difficult to directly measure the temperature of the filament so you have to use something other than a thermometer for the measurement. It should be possible to estimate the temperature of the filament from the light spectrum. Basically, treat the light bulb like a perfect black body radiator and use Plank's Law (http://en.wikipedia.org/wiki/Planck%27s_law) and the light spectrum of the bulb (for example http://www.graphics.cornell.edu/online/measurements/source-spectra/index.html) to calculate the temperature. Another way, which is a bit easier, is to use basic electronic theory to calculate the temperature of the filament that is required to produce the manufacturer's specifications for the bulb. For example, consider a typical 100 watt, 120 VAC light bulb with a tungsten filament. The bulb consumes (and radiates) 100 watts of power. A light bulb is a purely resistive load so Power=(Voltage)*(Current). Plugging in 100 watts as the power, 120 as the voltage (actually, that's the RMS voltage), and solving for current we get an RMS current of 0.83 amps. Since the bulb is just a resistor it obeys Ohm's Law; Voltage=(Current)*(Resistance). Our voltage is 120 and we determined the current to be 0.83 amps, so the resistance of the bulb when it is operating is 120/0.83= 144 ohms. If you take a 100W incandescent light bulb and measure its resistance at room temperature you get a value of about 15 Ohms. The difference between the room temperature resistance and the resistance when the bulb is operating is due to the affect of temperature on the filament's resistance. Metals (and conductors in general) increase their resistance as they are heated. The resistance at a particular temperature can be calculated with; R=Rref*(1 + alpha(T-Tref)] Where, R is the resistance at temperature T degrees Celsius. Rref is the resistance at a standard temperature Tref (often 0C or 20C). Alpha is the "temperature coefficient of resistance" for the material. For tungsten alpha=0.0044/C with a Tref of 20C (68F). If we assume that the 15 Ohm resistance at room temperature is close enough to the value at 20C (68F) then we can use Rref=15 ohms and R is the 144 ohms we calculated from the wattage and voltage of the bulb. Plugging these numbers into the equation; 144=15*(1 + 0.0044*(T - 20)) Solving for T (the temperature required to get the filament's resistance to 144 ohms) we get T=1975C (about 3600F). That's pretty hot! The filaments temperature will change if the applied voltage changes. The temperature will also be different from light bulb to light bulb (even if they have the same voltage and wattage ratings) since no two bulbs are exactly alike. An individual bulb will also change as it ages and as a function of the temperature outside the bulb.
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What is a filament light bulb?

the filament is the metal peice in a bulb that glows.Tungsten is most often used in a lightbulb.

What gas and filament is in an incandescent light bulb?

Most common house hold light bulbs are really just evacuated to really low pressures and contain a tungsten filament. the reason being is that tungsten has high resistivity an

Why is tungsten used in light bulb filaments?

Tungsten is used because it has a high melting point and retains its strength in temperature extremes. Tungsten-based alloys are used because tungsten has the highest melting

How long does a filament light bulb last?

It varies and the life of a bulb should be given on the packaging. Typical life of a normal bulb is 1000 hours, but it is possible to buy bulbs with 2000 or 3000 hour lifetime

Why does the light bulb not work when the filament is broken?

A light bulb works by passing an electric current through the filament, which is usually made from a high resistance substance such as tungsten. When the current flows through

What is the purpose of the filament in a light bulb?

The filament in a light bulb generates heat from the electrical current being drawn through the lamp and that heat is what creates the light shining out of the bulb.

How efficient is a filament light bulb?

about 10% the filament light bulbs give off about 90% heat and 10% light

What is filament of light bulb made of?

Filament of bulb is made up of Tungsten.  perfect answer:  filament of bulb made of tungsten because of its melting point tungsten s m.p. is 3422 c and it produces through a

Why is the filament of a light bulb made from tungsten?

Edison tried many different materials to invent a light bulb that works. After 1,000 failures he finally found tungsten worked best. Because of the heat, out of all the meta

Why is a light bulbs filament long and thin?

The first thing you have to look at for this is the equation for resistance in an object which is R = rho(L/A) where rho is a constant and L is length and A is cross sectional

Why does a light bulb filament glow?

The filament inside is heated. Once it gets hot enough, it dissipates some of the energy as heat and light.

Why is tungsten used in a light bulb filament?

The metal tungsten is used for the filaments in incandescent bulbs. It has a high melting point and retains its strength when heated. The tungsten's resistance makes it glow w

Element used in light bulb filament?

That depends on the bulb, and the time frame. The first bulbs had carbon filaments. Certain bulbs used in control devices have iridium filaments. Modern grocery store inca