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# Why is a light bulb a resistor?

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Most simple incandescent light bulbs are made of a thin section of tungsten through which the current flows.

This section of tungsten is called a "filament".

The tungsten filament has electrical resistance and so is a resistor.

As a resistor it develops a voltage drop. This voltage drop multiplied by the amperage passing through it equals the wattage of the bulb.

The heated tungsten gets to thousands of degrees above room temperature and becomes hot enough to produce yellow-white visible light.

As a resistor, the tungsten light bulb has a positive resistance coefficient.

This means that the electrical resistance goes up when the filament becomes hot.

For example, a 100 watt light bulb operated at 120 volts - it does not matter if it is AC or DC for this calculation - will have a resistance of 144 ohms when hot and draw .833 ampere.

When cold the filament typically has a resistance of only 10 ohms which increases as the filament heats up.

An interesting note:

The typical incandescent light bulb life is between 1000 and 2000 hours.

Some "long life" incandescent light bulbs simply have a thicker but longer section of tungsten and can run 5,000 to 20,000 hours or more without failing.

This type of bulb is sold to hotels and other places that want to reduce the replacement frequency of the bulbs.

If a manufacturer desired to do so they could make a light bulb which would last even longer than 20,000 hours by increasing the filament thickness but they feel that economically it would not be desirable for them, as they would sell less light bulbs.

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## Related Questions

It is the tungsten element in a filament light bulb that is the resistor. It is this resistance that produces light and heat.

The light bulb filament is made of a material fundamentally like the material used in resistors.

Among others, the filament of an incandescent light bulb is a resistor- which gives off heat and light.

It is an insulator because it brings in light and it has metal at the bottom. (metal is an insulator)

connect the light bulb to the positive wire like a inline fuse and then connect the wire to the battery it should just burn out the bulb

Yes it is. The filament in a standard incandescent bulb is a type of resistor. An incandescent light bulb contains tungsten which reduces electricity and converts electricity to heat and light. All incandescent bulbs are resistors, but only a fraction of resistors are bulbs. If you want to see if a bulb is a resistor, try adding another bulb in series without changing the voltage. Both bulbs will be very dim. Another way to test this is to get a multimeter and set the meter to the resistance setting. If you get any value other than zero, then it is functioning as a resistor.

wire a resistor across a battery. that is about as simple as it gets. the resistor could be an incandescent light bulb.

Most light bulbs don't have resistors; they are resistors. The filament introduces resistance as part of its action. The resistance is what makes it glow. Usually, if you use a resistor with a light bulb or other lighting device (neon tube, LED, etc), it is external. Its purpose is to reduce the voltage to match the requirements of the bulb. For instance, with a 50 ohm resistor, you could probably use a flashlight bulb with a 9 volt battery.

You have to list the devices for me to choose the device that uses the resistor to transform electrical electrical energy into light and heat. An electric light bulb will do.

Add a resistor between the power source and one side of the bulb.

The filament of a light bulb isn't like a resistor ... it is a resistor. The only difference from the ones on circuit boards is the it's designed to operate at a much higher temperature. So hot that it glows. The glass envelope is there to prevent oxygen from getting in and promptly burning it. When the filament becomes too hot it breaks breaking the current that was lighting it in the first place. That is why the light bulb "burns" out.

A resistor slows the flow of electricity, and converts the electrical energy into heat. You don't WANT heat - you want LIGHT, so we generally do not put resistors in lighting circuits. If there is a resistor in the circuit, it will cause some of the energy that would normally be converted to light to be converted into heat instead, so the light bulb will glow less brightly. A variable resistor in such a circuit is sometimes called a "dimmer".

Check the resistor. The little bulb shaped thing that has a socket. Most zappers have them.

A light bulb uses electricity as its source of energy.A light bulb to uses electrical energy which is supplied to a resistor that gives off heat as well as light. The resistor is a thin coiled piece of wire made of Tungsten because it has the highest melting point of any metal.For more information see the answer to the Related question shown below.

A resistor is really anything that uses electricity along an electric circuit, for example a light bulb, a computer, a radio, etc.

lower the voltage by using a different power source or by placeing a variable resistor in series with the light bulb.

A: NO it has resistance and act like a resistor but it is not linear like a resistor. So the part should be dignify with the proper name to tell all that that is not a resistor but a bulb.

It is a conductor, but the filament is a resistor : as current flows through the filament, some of the energy is released as heat and light.

The incandescent light bulb sends electrical current through a Tungsten filiment which resist the flow of current (it is the resistor). This resistance generates heat and makes the filiment glow. Tungsten has an extremely high melting point so it makes a good filiment for a bulb as it can glow brightly for a long time before giving out.

it is made of tungsten and is a resistor when current flows thru it it heats up and glows

Depends where you are planning to place the resistor.

Electricity creates heat when flowing through a resistor such as the filament in a tungsten light bulb, and, since the heat can not be readily conducted away in the near vacuum inside a light bulb, the heat eventually raises the temperature of the filament to a value that leads to radiation of light from the hot filament.

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