0
All devices obey Ohm's law. That is why its called a law.
The misunderstanding is that Ohm's law does not say that resistance is constant - it says that resistance is voltage divided by current.
Very few devices actually have constant resistance. Even the resistor is not constant, due to thermal properties.
AnswerI beg to differ with the previous answer.The term you are looking for is a 'linear' device. 'Non-linear' devices, on the other hand, include some semiconducting devices, such as diodes, but also includes certain metals such as tungsten. What it basically comes down to is that if there isn't a linear relationship between current and voltage, then the device is not obeying Ohm's Law!
Ohm's Law simply states that, 'providing external factors such as temperature remain constant, then the current flowing in a circuit is proportional to the applied voltage'. It most definitely doesn't say that 'resistance is voltage divided by current'!! In fact, it doesn't even mention resistance!
Ohm's Law is not an equation, despite it often being taught as such in high schools by teachers who should know better, but who misinterpret the Law by over-simplifying it (some high school teachers shouldn't even be teaching science, as they are responsible for many other misconceptions too!).
For current to be proportional to voltage, there must be a constant of proportionality. This is called conductance, expressed in siemens. However, it is more usual to use the reciprocal of conductance, which is resistance, expressed in ohms, that is: U = R I, where Ris a constant.
In other words, Ohm's Law is only true providing resistance is constant. So an incandescent lamp, for example, which uses the non-linear metal tungsten, as a filament, does not obey Ohm's Law. This is because its temperature increases significantly as the voltage across it is increased and, so, the resulting current does not increase proportionally with that voltage. Even 'linear' devices become 'non-linear' at some point, usually at extreme temperatures, once again reinforcing the fact that Ohm's Law only applies providing the temperature doesn't affect resistance.
To put it another way, if there isn't a straight line relationship between current and voltage, then the device ain't obeying Ohm's Law!
However, for any given voltage, you can certainly use the equation R = U/I to determine what the resistance happens to be at that particular voltage-but that isn't what Ohm's Law says. Ohm's Law isn't about a what happens at a particular voltage! It's about the current remaining proportional to the current over a wide range of voltage variation.
Wiki User
∙ 12y ago
Add your answer:
Earn +20 pts
State the imitation of ohm's law?
imitation of ohms law is that it can be applied only to linear devices it cannot be allowed to non linear devices...
What is a linear resistor?
which obey ohms law ANSWER: Not all potentiometers are linear some are made to follow a logarithm function some follows an exponential function. A linear potentiometer will have a linear curve. Materials that obey Ohm's Law are called 'linear' or 'ohmic'; those that don't are called 'non-ohmic' or 'non-linear'.
How do conductors obey the Ohm's law?
Very few conductors obey Ohm's Law, and its the rise in temperature of the conductor when current flows though it that prevents it from obeying Ohm's Law. Some alloys, such as constantan, obey Ohm's Law over a limited range because, over that range, changes in temperature don't affect their resistance. It's really time that we stopped teaching Ohm's Law, as it is not universal, and applies to very few conductors and hardly any electronic components!
Do transistors follow ohm's law?
As transistors are made of semiconductors, they do notfollow Ohm's law.A: they cannot follow exactly ohms law since they are themselves no linear active devices
How vacuum tubes do not obey ohms law in circuit design?
In point of fact, vacuum tubes do obey Ohm's law. Everything electrical obeys Ohm's law. The reason vacuum tubes don't appear to obey the law is that not every consideration takes into account the fact that vacuum tubs have dynamicresistance. Ohm's law, as applied to "pure" ohmic resistors, requires constant resistance, which no material, no matter how good, exhibits. In the real world, you have to consider that resistance can vary along with voltage and current, and this "complicates" things.
Do pure semiconductor obey ohms law?
No semiconductor's do not obey ohm's laws.
State the imitation of ohm's law?
imitation of ohms law is that it can be applied only to linear devices it cannot be allowed to non linear devices...
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.
What is a linear resistor?
which obey ohms law ANSWER: Not all potentiometers are linear some are made to follow a logarithm function some follows an exponential function. A linear potentiometer will have a linear curve. Materials that obey Ohm's Law are called 'linear' or 'ohmic'; those that don't are called 'non-ohmic' or 'non-linear'.
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')
How V equals IR in ohms law?
It doesn't! Ohm's Law simply states that for a limited range of conductors, the ratio of voltage to current is constant for variations in voltage. No mention of resistance. And Ohm's Law only applies to a relatively-small number of conductors; most materials and electrical devices such as diodes, etc., simply do no obey Ohm's Law. Those that do are called 'linear' or 'ohmic' materials or devices; those that don't are called 'non-linear' or 'non-ohmic'.The equation, V = IR (or, more specifically, R = V/I ) comes from the definition of the ohm, and NOT from Ohm's Law.
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
How do conductors obey the Ohm's law?
Very few conductors obey Ohm's Law, and its the rise in temperature of the conductor when current flows though it that prevents it from obeying Ohm's Law. Some alloys, such as constantan, obey Ohm's Law over a limited range because, over that range, changes in temperature don't affect their resistance. It's really time that we stopped teaching Ohm's Law, as it is not universal, and applies to very few conductors and hardly any electronic components!
According to Ohm's 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')
How do you calculate 1.67 ohms?
ohms law.
Do transistors follow ohm's law?
As transistors are made of semiconductors, they do notfollow Ohm's law.A: they cannot follow exactly ohms law since they are themselves no linear active devices
Where was georg Simon ohm born?
Ohm's most important discovery was in 1826 when he discovered the mathematical law of electric current called Ohm's law.
