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It means exactly what it sounds like. The resistance of an incandescent bulb's filament depends on its temperature. A filament has a positive temperature coefficient, which means that its resistance increases as its temperature increases. A typical 40 watt bulb (120 volts) has a cold resistance of about 28 ohms, but its hot, operating resistance is about 360 ohms. If the cold resistance were constant, the bulb would dissipate 379 watts. In fact, cold turn on is the most stressful time for a bulb.
What else can I help you with?
What is nonlinear resistance?
A nonlinear resistance is a resistance which is different for different voltages ie current is not proportional to voltage. An example of this is the filament of an incandescent lamp.
What is the current when a 60W lampis connected to 120v?
Since power is volts time amps, the current in a 60W lamp connected to 120V is 0.5A. Since a lamp is a resistive load, there is no need to consider power factor and phase angle, so that simplifies the explanation. ======================== Assuming this is an incandescent or halogen lamp (using a filament to make the light) there is a trick here: the resistance of a lamp filament varies with temperature and does not follow Ohm's law. The resistance will be much lower, thus the current will be much higher when the filament is cold, when the lamp is first connected. As the filament heats up, the resistance increases until it gets to a steady operating point of 0.5A. For a halogen lamp, the operating temperature is about 2800-3400K, so the R at room temperature is about 16 times lower than when hot... so when connected, the current is about 8A but drops rapidly. The current could be even higher if the lamp is in a cold environment. Non-halogen lamps operate at a lower temperature and would have a lower initial current--about 5A. And this all assumes the lamp is rated for 120V. If it is a 12V/60W lamp, the filament will probably break and create an arc, which may draw a very large current.
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 . :)
What is the part of the light bulb that glows?
In an incandescent lamp, it is called a filament. It is usually made out of Tungsten. The resistance in the filament causes it to heat up, and then glow. In a neon lamp it is plasma, which is an ionized gas. In a fluorescent bulb mercury vapor is ionized to produce UV radiation, that hits the phosphor coating on the outside of the bulb and that glows.
What type of light contains a filament?
All kinds of incandescent lamp, and all types of light bulb contains filament. But there are several kinds of filament applied each type of light bulb.
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.
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.
What is the nature of the slope of the viltage vs resistance in filament lamp?
The relationship between the voltage and resistance in a filament lamp is non-linear. As the voltage increases, the resistance in the filament of the lamp also increases due to the heating effect. This increase in resistance causes the current to increase at a slower rate than expected, leading to a non-linear slope in the voltage-resistance graph.
Does a lamp with a thick filament draw more current 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.
Why is the filament inside an electric lamp made very fine?
The filament is fine so that its electrical resistance can be quite high. It is also long, for the same reason. Usually it is coiled up to fit the length in the lamp. The heating effect of electric current is proportional to the current squared, time the resistance (I*I*R). Most of the effect is due to the current. The current through the filament must be limited to stop it melting. Adding resistance will do that. Taking resistance away increases heating. So, a low energy lamp has a very thin filament and a high energy lamp will have a thicker filament.
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.
Why is a filiament lamp a non ohmic conductor?
A filament lamp is a non-ohmic conductor because its resistance changes with applied voltage. As the voltage increases, the resistance also increases. This is due to the temperature-dependent behavior of the filament material, which causes the resistance to vary.
What is nonlinear resistance?
A nonlinear resistance is a resistance which is different for different voltages ie current is not proportional to voltage. An example of this is the filament of an incandescent lamp.
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 does a filament lamp get hot when you use high voltage?
because there is a correlation between resistance and voltage and current. The equation resistance = voltage divided by current shows that the higher the voltage, the bigger the resistance,, and the bigger the resistance the hotter the filament lamp will get because of the electrons bumping into each other which means there is a loss of energy and that energy is being transferred to the filament making the actual filament bulb hot since there is more thermal energy wasted at the end.
WhY does a filament lamp get when you us high voltage?
because there is a correlation between resistance and voltage and current. The equation resistance = voltage divided by current shows that the higher the voltage, the bigger the resistance,, and the bigger the resistance the hotter the filament lamp will get because of the electrons bumping into each other which means there is a loss of energy and that energy is being transferred to the filament making the actual filament bulb hot since there is more thermal energy wasted at the end.
Why is there a curve and not a straight line in the graph for a filament lamp?
I had to answer this and found out that............ The line on the graph that represents the filament lamp is curved because the resistance of it increases with supplied voltage Hope this is alright for you :) x
