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A tungsten filament does follow Ohm's Law at any instant of time. You may be confused in that the filament resistance changes from its "cold" state to its "hot" state. When cold the resistance is about 1/15 the resistance of what it is when the filament heats up, which happens very quickly. At any instant Ohm's Law holds. When the voltage is applied you have an initial current draw that exceeds the steady state current draw based on the change in resistance.
AnswerOhm's Law either applies, or it does not. It cannot apply 'at an instant of time' -a change in current is either proportional to a change in voltage, or it isn't!
A tungsten filament does not obey Ohm's Law, because the current flowing through the filament does not increase in proportion to the applied voltage. This is because the resistance changes due to the filament's increasing temperature as the applied voltage increases. This is why Ohm's Law specifies that current is proportional to voltage, provided the temperature remains constant.
Although tungsten doesn't obey Ohm's Law, the so-called Ohm's Law equation applies whether a circuit obeys Ohm's Law or not. This is because the formula is really derived from the definition of the ohm, and not from Ohm's Law itself, which makes absolutely NO reference to resistance!
Wiki User
∙ 10y ago
Wiki User
∙ 11y agoIt does. Everything obeys the LAW.
The fillament uses the energy to create heat and light.
AnswerIt is quite incorrect to say that 'everything obeys Ohm's Law'. In fact, relatively few materials obey Ohm's Law.
The reason that a filament lamp does not obey Ohm's Law is because, for tungsten, the ratio of voltage to current isn't constant for variations in voltage, which is the requirement for Ohm's Law.
The requirement for Ohm's Law is linearity. If there isn't a linear relationship between voltage and the resulting current, then Ohm's Law does not apply. So, Ohm's Law does not apply to a great many alloys, to most semiconductors, to vacuum tubes, and to gas and liquid conductors.
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According to ohms law what is the resistance of a light if the voltage is 9.0 volts and the current is 0.30 amps?
30 ohmsAnswerAn incandescent lamp doesn't obey Ohm's Law, because the ratio of voltage to current changes as the supply voltage is varied. All you can say is that, when the applied voltage is 9.0 V, then the resistance will happen to be 30 ohms. If you change the applied voltage to some other value, then you will find the resistance will have changed too. Ohm's Law isn't a universal law; in fact, most materials and circuit devices do not obey Ohm's Law, and tungsten, from which lamp filaments are manufactured, is an example of a metal that does not obey Ohm's Law (we call them 'non-linear' or 'non-ohmic')
Why is Ohms Law important?
The simple answer is that it isn't! Ohm's Law applies to so few conductors and electrical devices that it hardly qualifies as a 'law' at all. For Ohm's Law to apply, the ratio of the voltage across a conductor (or any sort of load) to the current through that conductor must be constant for variations in voltage, and this occurs in very few conductors.Many people, who should know better, mistakenly believe that the equation, R = V/I, represents Ohm's Law. This is incorrect, as the equation is derived from the definition of the ohm (being defined as a 'volt per ampere'), and not from Ohm's Law. This equation is universal, and applies in situations where Ohm's Law doesn't. For example, the ratio of voltage to current for a tungsten lamp changes as the voltage across the filament changes and, so, tungsten doesn't obey Ohm's Law. However, for any particular voltage, the resistance of tungsten AT THAT VOLTAGE can be determined by the equation.Many scientists and engineers believe that Ohm's Law should be a law at all. A well-known MIT professor, for example, goes as far as to say that "Ohm's Law is a fake"! In my opinion, there doesn't seem to be any good argument for teaching Ohm's Law beyond its historical significance.
Application of other conductors which does not obey ohms law in a circuit?
Ohms law is a law; all conductors must obey it. A simple form of ohm's law is V = I / R. The only control a conductor has on this equation is in the 'R'. Super conductors, for example, have a resistance that approaches zero at certain termperatures. This does not mean that they break the law, though.AnswerOhm's Law describes a linear relationship between the potential difference across a conductor; it has nothing to do with the relationship between potential difference, current, and resistance.The equation R = E/I is derived from the definition of the ohm, and not from Ohm's Law. This equation applies whether Ohm's Law is obeyed or not.In fact, relatively few conductors obey Ohm's Law. Those that do are termed 'ohmic' or 'linear' conductors; those that don't are termed 'non-ohmic' or 'non-linear'.Simply put, if the graph representing current plotted against a varying potential difference is not linear, then it ain't obeying Ohm's Law!
What are the release dates for Obey the Law - 1933?
Obey the Law - 1933 was released on: USA: 11 March 1933
Write mathematical form of ohms law?
The mathematical form of Ohms law is I=V divided by R. I is current, V is voltage while R is the resistance.
Is ohms law applicable to filament?
Absolutely not! A tungsten filament is an example of a non-linear or non-ohmic material, and it does not obey Ohm's Law. Ohm's Law is a law of constant proportionality; in other words, for it to apply, the ratio of voltage to current must be constant over a wide range of voltages. Increasing the voltage of a tungsten filament to its rated voltage causes its resistance to increase around 15 - 18 times, compared with its 'cold' resistance. Therefore, the ratio of voltage to current changes significantly as the applied voltage changes -so it does not obey Ohm's Law.However, the ratio of voltage to current will always tell you what the resistance happens to be for any particular ratio. Since, for tungsten, because the ratio increases as the voltage increase, the resistance changes too.To summarise, for Ohm's Law to apply, there MUST be a linear relationship between voltage and current; with tungsten, the relationship is a curved line and, so, it is non-linear and does not obey Ohm's Law.
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.
Do pure semiconductor obey ohms law?
No semiconductor's do not obey ohm's laws.
Is a light bulb an inductive load or resistive load?
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.
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!!
Is non ohmic filament better than ohmic filament?
How can a filament give off heat without resistance?Another AnswerThe terms, 'ohmic' and 'non-ohmic' refer to whether or not a material obeys Ohm's Law. It has NOTHING to do with whether a filament is resistive or not!Ohmic materials obey Ohm's Law; non-ohmic materials do not.GSL incandescent lamps generally use a filament made of tungsten. If you were to apply a gradually-increasing voltage to that filament, and note the corresponding values of current and, then, plot the results in the form of a graph, you would find that the graph is a curve. For Ohm's Law to apply, the current must be proportional to voltage for variations in voltage and this is ONLY true for a straight-line graph. Tungsten, therefore, is non-ohmic and does not obey Ohm's Law.Tungsten is chosen for lamp filaments because it can withstand very high temperatures without failing. This is the main reason that it is chosen, NOT because it is non-ohmic.
Why is a graph of voltage against current for a filament bulb curved?
Because as current increases, heat increases and therefore resistance increases. Since resistance is the gradient of the graph, the gradient will increase and therefore the graph will curve. (The filament in the bulb is an non-ohmic conductor; its resistance is only constant at a constant temperature.)Another AnswerIncandescent lamp filaments are manufactured from tungsten. Tungsten is classified as 'non-ohmic' or 'non-linear', which means that (in common with most materials, in fact) it does not obey Ohm's Law. For a material to obey Ohm's Law, the ratio of voltage to current (i.e. its resistance) must remain constant for variations in voltage -as you have discovered, tungsten doesn't do this, producing a curve, rather than a linear, graph. As the original answer indicates, the temperature coefficient of resistance of tungsten in such that, as it gets warmer, its resistance increases.Those few materials that do obey Ohm's Law are called 'ohmic' or 'linear' materials.
Why tungsten filament bulb is preferred in stefan's law experiment?
because it has high meting point to withstand high temperature.
According to ohms law what is the resistance of a light if the voltage is 9.0 volts and the current is 0.30 amps?
30 ohmsAnswerAn incandescent lamp doesn't obey Ohm's Law, because the ratio of voltage to current changes as the supply voltage is varied. All you can say is that, when the applied voltage is 9.0 V, then the resistance will happen to be 30 ohms. If you change the applied voltage to some other value, then you will find the resistance will have changed too. Ohm's Law isn't a universal law; in fact, most materials and circuit devices do not obey Ohm's Law, and tungsten, from which lamp filaments are manufactured, is an example of a metal that does not obey Ohm's Law (we call them 'non-linear' or 'non-ohmic')
When does a thermostor obey ohm's law?
I hope you mean the thermistor. If so,well it does not obey Ohms law. When current flows through the thermistor its temperature start increasing which reduces the resistance of the thermistor. A reduction in resistance at the same supply voltage will cause the current to increase. Thus it's not obeying Ohms law.
Is ohms law applicable to 60 watt bulb?
Ohm's Law doesn't apply to an incandescent lamp, regardless of its power rating. This is because the filament is manufactured from tungsten which is a 'non-ohmic' or 'non-linear' conductor, which means that the ratio of voltage to current changes for variations in voltage. For Ohm's Law to apply, this ratio must remain constant for variations in voltage.
Why does ohm's matter with speakers?
the vibration produced in the coil of a speaker is due to current passing through it hence it obey ohms law
