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Voltage squared equals current times resistance, so voltage squared divided by power equals resistance. So, for a 60W bulb: * (120V)^2 / 60 = R * 14400 / 60 = 240 ohms Keep in mind this is after the bulb reaches operating temperature. The resistance of the filament is temperature dependent.
Wiki User
∙ 16y ago
Wiki User
∙ 12y agoThat's going to depend completely on what voltage it's designed to be
powered from, and how much power it's expected to dissipate when that
voltage is impressed across it.
240 volts, 60 watts:
P = E2/R
R = E2/P = (240)2/60 = 960 ohms
120 volts, 100 watts:
R = E2/P = (120)2/100 = 144 ohms
120 volts, 5 watts (night light):
R = E2/P = (120)2/5 = 2,880 ohms
Wiki User
∙ 14y agoresistance is measured in Ohms
Resistance = voltage divided by current : R = V / I
so R = 110V / 1.4A = 78.57 Ohms
Wiki User
∙ 13y agoThere's really no telling, as it will depend on the voltage, the power of the lamp, and what type of lamp it is. /bulb, tube, diode etc.)
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If the tungsten filament of a lamp has a cross-sectional are of 5x10-9 m2 how long must it be have a resistance of 120 ohms at 20 degrees Celsius?
If the tungsten filament of a lamp has a cross-sectional area of 5x10-9m2,how long must it be to have a resistance of 120 ohms at 20 degree celsius?
What is the thin wire inside a bulb called?
It is called a filament and usually made of tungsten steel.
Does ohm's law also apply to the filament lamp?
No. For Ohm's Law to apply, the ratio of voltage to current must remain constant for variations in voltage. This simply doesn't happen with a tungsten filament. In fact, MOST materials don't obey Ohm's Law.
In parallel circuit whathappens to the total resistance if one branch opens-Provide an example?
In a parallel circuit, each load added subtracts from total resistance. When one or more loads is removed from a parallel circuit, the total resistance is increased, reducing the total amperage draw. The less resistance a load has, the more current can pass through. This is part of Ohm's law. The mathematical equation that describes Ohm's law is: I=V/R , where I is the current in amperes, V is the potential difference in volts,and R is a circuit parameter called the resistance For example : The humble light-bulb is rated by the watts it uses. The amount of watts used by a light-bulb is calculated using Ohm's law. With the resistance of the bulb's filament and the voltage the bulb is designed to operate with, one can derive the amperage the bulb will draw. The amperage is then multiplied by the voltage to show wattage. Using Ohm's law : With the resistance of a 40watt 120volt light-bulb, only 0.33amps is able to pass through the bulb's 363ohm filament at 120volts. A lamp that has two 40watt bulbs inplace, and the two bulbs are in parallel, the circuit will have a resistance of 179ohms and draw 0.67amps which is 80watts at 120volts.
Why does a bulb glow when electric passes through it?
The filament in the bulb has resistance. The current flowing through the resistance of bulb causes the filament to dissipate energy in the form of heat and light. The filament is actually glowing white-hot because of the energy it is dissipating, thus giving 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.
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.
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 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.
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
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 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.
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.
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.
Graph of resistance of filament lamp against potential difference?
It will vary from 0 to a certain value but at a slower rate.
Why does the filament lamp does not follow Ohms Law give any example?
A filament's resistance value varies with temperature. When directly measuring resistance, the filament is off, and at or near room temperature. When the circuit is turned on to measure voltage and current, the filament's temperature will increase and the resistance value will increase. This makes it appear as though Ohm's law is wrong.AnswerThere is no difficulty; your experiment will simply prove that the filament of the lamp doesn't obey Ohm's Law.When you plot the results of current against voltage for a lamp's filament, obtained from your experiment, the result will be a curved line, indicating that the current is notproportional to voltage (due to a changing resistance). This shows that the filament doesn't obey Ohm's Law. To obey Ohm's Law, the result must be a straight-line graph.Although the resistance of the lamp can be found at any point along the curve from the ratio of voltage to current (i.e. R = V/I) at that particular point, the lamp does not obey Ohm's Law. Ohm's Law only applies when the ratio of voltage to current remains constant throughout the experiment.So no difficulty has arisen with your experiment, you have simply proved that Ohm's Law doesn't apply to the lamp filament. Believe your results!!
What part of the lamp converts electricity to light?
For a filament-type (incandescent) lamp, it's the filament.
