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Does the resistance of a light bulb filament change after the light has been turned on?
Wiki User
∙ 14y ago
The electrical resistance of a light bulb increases when it is turned on
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.
Wiki User
∙ 13y ago
Wiki User
∙ 13y agoThe electrical resistance of a light bulb increases when it is turned on
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.
Wiki User
∙ 14y agoYes. The resistance of a light bulb filament increases as it gets hotter. It is not unusual for a bulb's cold start power to be ten times its running power. A typical incandescent 60W bulb may have a cold resistance of 30 ohms, 500W, with a hot resistance of 240 ohms, 60W.
Wiki User
∙ 11y agoThe hotter it gets the more the resistance becaomses.
Wiki User
∙ 13y agoAs the bulb gets hotter, the resistance increases.
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Is resistance in the filament of a lamp essential or not?
Yes, the resistance of the filament of a light bulb is what generates enough heat to make the filament glow and produce light.
What did Joseph swan invent?
Joseph Swan invented the carbon filament because to see light back in the days. Which turned out to be a light bulb.
Why does a wire connected to a bulb not glow where as the filament of the bulb glows when the same current is passed through both connections?
It glows because the filament wire is exposed in a vacuum and electrically, the light is a high resistance load. You know the sparks you get when you rub two exposed hot electrical wires together? That's a dead short. Now, put that short in a vacuum where the wire can't oxidize, and presto! Incandescent light. The filament is made of tungsten, and tungsten has a very, very, very high melting point. It took Thomas Edison a long time to find it, but find it he did.
What is the filament used in tubelight-?
The type of filament used in tube light is that one which is thin and surrounded by an oblong metal shield.
What is an incandascent lamp?
Your standard light bulb where a filament is heated by a current passing through it. The heated filament then gives off light.
Is resistance in the filament of a lamp essential or not?
Yes, the resistance of the filament of a light bulb is what generates enough heat to make the filament glow and produce light.
What does the filament of a light bulb allows the light bulb to change electrical energy to?
The filament of a light bulb overs enough resistance to current flow, that the filament heats up so much that it will glow and produce visible light.
When the bulb is the resistance what this tells about the resistance?
An incandescent bulb has a filament that has a resistance. The value of the resistance determines the current that will flow for a given supply voltage. The heat generated by the current flowing through the filament gives off light. As the resistance of the filament decreases the current increases and you get more light.
What is the general resistance of a tungsten filament?
The resistance of the filament in a light bulb is(voltage at which the bulb is designed to operate)2/(the rated power/watts of the bulb)
Is a light bulb a soure of light?
Yes, a light bulb is a source of light. When current is going through the filament the resistance generates enough heat that the filament glows, producing light.
What does the filament in a light bulb do to the electricity?
The filament in a light bulb forms resistance so that heat can happen. The electricity then converts to light energy and heat energy so that the light will shine.
What was a resistance invention?
The incandescent light bulb. The tungsten filament lights due to it's resistance of the current flowing through it.
What happens to the energy when you turn on an electric lamp?
Electricity flows through the filament, resistance in the filament causes heat and light energy to be created.
What is the purpose of the filament inside the light bulb?
The filament is a special metal composition of tungsten that conducts current and heats up and emits light as a result of the current and its internal resistance.
Why do light filament bulbs usually blow when they are first switched on?
because when they are first switched on a large surge of electrical current flow through a cold filament. When you first switch on the bulb the resistance is small, so you get a current surge which breaks the weakened filament. The filament is weakened by repeated heating and cooling from the bulb being turned on and off; which makes it brittle.
What happens when a battery light the light bulb?
When the switch is turned it completes an electrical circuit. The circuit amperage flows through a high resistance filament in the bulb and it starts to glow. The bright glow from the filament and the reflector behind the bulb is what creates the flashlights beam.
What causes incandescent light bulbs to produce light?
The filament in the bulb has a high resistance to the flow of electricity. As electricity passes through it, the filament heats up and begins to glow, giving off the visible light you see.
