Cameron Miranda
Ohm's law states the relationship between electric current and potential difference. It is one of the most basic and important laws of electric circuits. However, it is not a universal law as it is only applicable to ohmic conductors such as iron and copper when physical conditions like temperature and pressure are constant. Non-ohmic conductors like semiconductors, diodes, and vacuum tubes do not obey Ohm's law as their conductance changes with variations in physical factors, resulting in nonlinear behaviour.
| Characteristics | Values |
|---|---|
| Applicability to conductors | Ohm's law is applicable to ohmic conductors such as iron, copper, and manganese wires but not to non-ohmic conductors like semiconductors. |
| Applicability to devices | Ohm's law does not apply to semiconducting devices, unilateral devices like diodes, and other nonlinear devices. |
| Sensitivity to physical conditions | Ohm's law assumes constant physical conditions like temperature and pressure, and deviations from these conditions may yield inaccurate results. |
| Applicability to all conducting elements | Ohm's law is not universally applicable to all conducting elements. |
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What You'll Learn
Ohm's Law and its inapplicability to non-ohmic conductors
Ohm's law is not a universal law. It is dependent on the physical factors of the conductor, such as temperature and pressure. If the physical conditions of the conductor, such as temperature, length, and pressure, are not kept constant, Ohm's law may not give the desired results.
Ohm's law applies to ohmic conductors such as iron and copper. It states the relationship between electric current and potential difference. The current that flows through most conductors is directly proportional to the voltage applied to it. Mathematically, this current-voltage relationship can be written as V=IR, where V is the voltage, I is the current, and R is the resistance.
However, Ohm's law is not applicable to non-ohmic conductors such as semiconductors. Non-ohmic conductors are materials or devices that do not follow Ohm's law. They are nonlinear devices, meaning that the ratio of voltage to current does not remain constant for variations in voltage. Examples of non-ohmic conductors include germanium, silicon, tungsten, LED, transistors, vacuum tubes, diodes, and triode bulbs.
The inapplicability of Ohm's law to non-ohmic conductors is because the relationship between current and voltage in these materials is nonlinear. In other words, the resistance of the material is not constant but varies with factors such as voltage and temperature. For example, in a light bulb, as the current is increased, the temperature of the filament rises, and the resistance of the filament changes. This violates Ohm's law, which assumes that the resistance remains constant.
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Ohm's Law and the behaviour of semiconductors
Ohm's law is not a universal law as it is only applicable to ohmic conductors such as iron and copper. It does not apply to non-ohmic conductors like semiconductors, which are nonlinear devices. The ratio of voltage to current in semiconductors is not constant for variations in voltage.
Ohm's law states the relationship between electric current and potential difference. It states that the voltage across a conductor is directly proportional to the current flowing through it, as long as all physical conditions and temperatures remain constant. The law can be expressed mathematically, with the constant of proportionality, R, representing resistance and measured in ohms (Ω).
However, Ohm's law fails to explain the behaviour of semiconductors. Semiconductors have more constraints than metallic conductors, as there can be a limited number of carriers available. This means that their velocity becomes significant compared to thermal motion, and Ohm's law is no longer applicable. Additionally, higher voltages can affect the boundary conditions at the surfaces of semiconductors, impacting their DC resistance.
Some sources suggest that under normal conditions and at fixed temperatures, all materials, including semiconductors, will follow Ohm's law to some extent. However, it is important to note that Ohm's law is just an approximation, and there are exceptions where the relationship between voltage, current, and resistance becomes more complex. For example, in cases where increasing the current raises the temperature, such as in a lightbulb filament, Ohm's law cannot be applied.
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Ohm's Law and the impact of physical conditions
Ohm's law is not a universal law. It is only applicable to ohmic conductors like iron and copper when all physical conditions and temperatures remain constant. The law states the relationship between electric current and potential difference, where the current that flows through most conductors is directly proportional to the voltage applied to it.
The impact of physical conditions on Ohm's law is significant. For example, in a lightbulb, the filament violates Ohm's law because the temperature rises as the current is increased. Similarly, in certain components, increasing the current raises the temperature, and Ohm's law cannot be applied.
Ohm's law is dependent on the physical factors of the conductor, such as temperature, pressure, and length. It is important to note that non-ohmic conductors like semiconductors do not obey Ohm's law because they are nonlinear devices. The ratio of voltage to current in semiconductors is not constant for variations in voltage.
Additionally, unilateral devices like diodes and vacuum tubes do not follow Ohm's law. The conductance of these devices changes with temperature, resulting in a non-linear relationship between voltage and current.
Ohm's law is a fundamental concept in electrostatics and electrical engineering, providing a basic relationship between voltage and current in electric circuits. However, it has limitations and is not universally applicable to all conducting elements.
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Ohm's Law and the behaviour of unilateral devices
Ohm's law is not a universal law as it is only applicable to ohmic conductors such as iron and copper. It does not apply to non-ohmic conductors like semiconductors. Non-linear devices such as semiconductors have a current that is not proportional to the applied voltage, meaning the voltage-to-current ratio does not remain constant when voltage varies.
Ohm's law states the relationship between electric current and potential difference. The current that flows through most conductors is directly proportional to the voltage applied to it. The voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperatures remain constant.
The behaviour of semiconductors and unilateral devices like diodes defines Ohm's law. Unilateral devices are those in which the current can only flow in one direction. Diodes, transistors, and other electronic components are used in these sorts of networks.
Ohm's law does not apply to unilateral networks. Non-linear components are also exempt from Ohm's law. The thyristor is an example of a non-linear element. The resistance value of non-linear elements varies depending on the voltage and current.
Ohm's law may not give the desired results if the physical conditions such as temperature or pressure are not kept constant.
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Ohm's Law and the behaviour of current flow
Ohm's Law states the relationship between electric current and potential difference. The current that flows through most conductors is directly proportional to the voltage applied to it. The law was discovered by German physicist Georg Simon Ohm and published in his 1827 paper, 'The Galvanic Circuit Investigated Mathematically'. Ohm's Law is considered one of the most basic and important laws of electric circuits.
The law states that the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperatures remain constant. Ohm's Law can be written mathematically as V=IR, where V is voltage, I is the current, and R is resistance. The constant of proportionality, R, is called Resistance and has units of ohms, with the symbol Ω.
The hydraulic analogy is often used to explain Ohm's Law. In this analogy, voltage is analogous to water pressure, current is the amount of water flowing through the pipe, and resistance is the size of the pipe. More water will flow through the pipe (current) when more pressure is applied (voltage), and the bigger the pipe (lower the resistance).
Ohm's Law can be used to determine the values of voltage, current, and resistance in a circuit. If the values of any two of these quantities are known, Ohm's Law can be used to calculate the third.
However, it is important to note that Ohm's Law is not a universal law. This is because it is only applicable to ohmic conductors such as iron and copper, and does not apply to non-ohmic conductors like semiconductors. Non-ohmic devices, such as LEDs, introduce a "voltage drop" into the circuit, changing the amount of current flowing through it. Additionally, Ohm's Law fails to explain the behaviour of semiconductors and unilateral devices such as diodes, and may not give accurate results if physical conditions such as temperature and pressure are not kept constant.
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Frequently asked questions
No, Ohm's Law is not a universal law. It is only applicable to ohmic conductors like iron and copper and depends on the physical factors of the conductor, such as temperature and pressure.
Examples of non-ohmic conductors include semiconductors, diodes, vacuum tubes, LEDs, liquid electrolytes, and solar cells.
Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied. However, in non-ohmic conductors, the relationship between current and voltage is nonlinear, resulting in a curved graph rather than a straight line.
