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What advantages and disadvantages does the filament lamp have by having a filament which shows increasing resistance with current?
The advantage is that the bulb will auto stabilize at a certain power level once it reach equilibrium. The disadvantage is that turn on is stressful, and that there is a limited number of turn on cycles available.
The best of both worlds can be achieved with a soft turn on circuit, but most lamps don't do that. My nightstand lamp does, and the bulb lasts five times longer than usual, but the cost savings is uncertain, because that circuit is not available anymore.
What else can I help you with?
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.
Does the resistance of a light bulb filament change after the light has been turned on?
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.
Why does the filament lamp does not follow Ohms Law give any example?
Well, honey, the filament lamp doesn't give a hoot about Ohm's Law because its resistance changes with temperature. As the current increases, the temperature of the filament rises, causing the resistance to also increase. It's like trying to control a wild horse - good luck getting it to follow any law!
Why the slope of voltage-resistance characteristic increases in the case of tungsten lamp and decresing in case of carbon lamp?
If the filament really was made from a material that has a negative temperature coefficient (as temperature increases, resistance decreases) then the decreasing resistance would cause more and more current to be taken as the lamp heated up and the temperature would get higher and higher in a runaway manner until either the power supply's breaker would trip or (more likely) the light bulb's filament would simply burn open. In fact the filament has to be made from a material that has a positive temperature coefficient. (As temperature increases, resistance increases.) Then, as the bulb's temperature rises, its filament's increasing resistance causes less current to be taken than when it was cold. Quite quickly a stable "steady-state" temperature and "running" resistance is reached so that the bulb simply continues to give out a steady amount of light according to the current it is taking from the electricity supply.
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.
Which has the thickest filament - a high-resistance or a low-resistance bulb?
A high-resistance bulb typically has a thicker filament compared to a low-resistance bulb. The thicker filament in a high-resistance bulb can withstand the greater heat generated by the increased resistance, resulting in a longer lifespan for the bulb.
Why does the resistance of a filament bulb depend on the current in the bulb?
The resistance of a piece of wire changes with temperature. In a filament bulb the wire is heated to about 3000 degrees C so a large change in resistance can be expected. A 240 v 105 w halogen bulb has a cold resistance of 35 ohms, but when running its resistance is 549 ohms.
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.
Why does the resistance of a filament depend on the current?
The resistance of a filament depends on the current flowing through it because as current flows through the filament, it heats up due to the electrical energy converting into heat energy. This increase in temperature causes the resistance of the filament to increase, resulting in a higher overall resistance in the circuit.
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.
Does the resistance of a filament light bulb change as the bulb gets brighter?
Yes, the resistance of a filament light bulb increases as the bulb gets brighter. This is due to the increase in temperature of the filament, which causes the resistance to go up.
Graph of resistance of filament lamp against potential difference?
As potential difference increases in a filament lamp, resistance also increases due to an increase in temperature. The relationship between resistance and potential difference in a filament lamp is non-linear due to the temperature-dependent nature of resistance in the filament material. At low voltages, the resistance is relatively low, but as the temperature of the filament increases with higher voltages, the resistance also increases.
Why does the filament become hot?
The filament becomes hot when electricity passes through it, due to resistance in the wire. This resistance causes the filament to heat up and emit light in an incandescent bulb.
Why do the reading differ for increasing and decreasing values of the lamp voltages?
at the time of decreasing lamp voltage as the temperature is already high the gas in the lamp is already in ionized state leading to different resistance ,but when increasing voltage the gas is not in ionized state it ready to ionize ,so there is slightly variation in resistance . :)
Why filament gets heated?
Filament gets heated when an electric current passes through it, causing resistance in the filament wire. The resistance converts electrical energy into heat energy, which then causes the filament to reach high temperatures and emit 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)
Does a lamp with a thick filament draw more or less current than a lamp with a thin filament?
A lamp with a thick filament will draw more current. What restricts the current flow in the filament is the resistance of the filament which increases as the temperature of the filament increases. A thin filament requires less energy to get heated up that a thick one so less current to achieve threshold resistance. Also a thick filament provides a broader path for current so there is less resistance per increase in degree centigrade. For these two (closely related but distinct) reasons it will require more current for the filament to get heated up to threshold resistance.
