1 Answer
Ohm's Law is a fundamental principle that describes the relationship between voltage (V), current (I), and resistance (R) in electrical circuits, expressed as:
\[
V = I \times R
\]
However, Ohm's Law is not applicable everywhere, especially in certain conditions. Here’s why:
1. Non-linear Materials:
Ohm’s Law assumes that the material through which the current flows has a constant resistance. But in many materials (like diodes, transistors, or certain metals), the resistance changes depending on the voltage or current. These materials don’t follow Ohm’s Law because their relationship between current and voltage is not linear.
2. High Voltages or Currents:
At very high voltages or currents, certain materials or components may exhibit non-linear behaviors, leading to deviations from Ohm’s Law. For example, when the electric field becomes very strong, it can cause the material to break down or behave in unexpected ways (like in the case of electrical arcs).
3. Superconductors:
At extremely low temperatures, some materials become superconductors, which means they have zero resistance. In these cases, Ohm’s Law doesn't apply the way it typically does because there’s no resistance to account for.
4. Semiconductors:
Semiconductors, such as silicon, don’t follow Ohm's Law in the simple sense. Their resistance changes with temperature and the applied voltage, especially when used in components like diodes or transistors. The relationship between current and voltage is more complex.
5. Time-Varying Fields:
Ohm’s Law doesn’t apply well to situations involving alternating current (AC) at high frequencies or where electromagnetic fields change over time. In these cases, impedance and reactance (which involve resistance, inductance, and capacitance) become more important than simple resistance.
When does Ohm’s Law apply?
It’s most accurate when dealing with ohmic materials—materials where the current-voltage relationship is linear and constant, like resistors and conductors under normal conditions. For these, Ohm’s Law works great!
In short, while Ohm's Law is foundational and widely used in basic electrical circuits, there are specific situations (non-linear materials, high voltages, etc.) where it doesn't hold true.
\[
V = I \times R
\]
However, Ohm's Law is not applicable everywhere, especially in certain conditions. Here’s why:
1. Non-linear Materials:
Ohm’s Law assumes that the material through which the current flows has a constant resistance. But in many materials (like diodes, transistors, or certain metals), the resistance changes depending on the voltage or current. These materials don’t follow Ohm’s Law because their relationship between current and voltage is not linear.2. High Voltages or Currents:
At very high voltages or currents, certain materials or components may exhibit non-linear behaviors, leading to deviations from Ohm’s Law. For example, when the electric field becomes very strong, it can cause the material to break down or behave in unexpected ways (like in the case of electrical arcs).3. Superconductors:
At extremely low temperatures, some materials become superconductors, which means they have zero resistance. In these cases, Ohm’s Law doesn't apply the way it typically does because there’s no resistance to account for.4. Semiconductors:
Semiconductors, such as silicon, don’t follow Ohm's Law in the simple sense. Their resistance changes with temperature and the applied voltage, especially when used in components like diodes or transistors. The relationship between current and voltage is more complex.5. Time-Varying Fields:
Ohm’s Law doesn’t apply well to situations involving alternating current (AC) at high frequencies or where electromagnetic fields change over time. In these cases, impedance and reactance (which involve resistance, inductance, and capacitance) become more important than simple resistance.When does Ohm’s Law apply?
It’s most accurate when dealing with ohmic materials—materials where the current-voltage relationship is linear and constant, like resistors and conductors under normal conditions. For these, Ohm’s Law works great!
In short, while Ohm's Law is foundational and widely used in basic electrical circuits, there are specific situations (non-linear materials, high voltages, etc.) where it doesn't hold true.