Ohm’s law fails to describe the behavior of materials that do not have a constant resistance. Non-ohmic materials, such as semiconductors and insulators, have a resistance that varies with voltage or current, making Ohm’s law inaccurate for these materials. Devices like diodes and transistors, which are integral to modern electronics, do not follow Ohm’s law because their resistance changes with applied voltage.
In certain situations, Ohm’s law fails to apply accurately. For instance, in high-frequency AC circuits, the inductive and capacitive reactance becomes significant, affecting the overall impedance in ways that Ohm’s law does not account for. Similarly, in superconductors, which exhibit zero resistance below a critical temperature, Ohm’s law does not hold because the voltage drop across them is zero regardless of the current.
Ohm’s law does not work in cases involving materials with non-linear current-voltage characteristics. An example is the filament of an incandescent light bulb, which has a resistance that increases with temperature. As the filament heats up with increased current, its resistance changes, leading to a non-linear relationship between voltage and current, thus violating Ohm’s law.
The failures of Ohm’s law arise because it assumes a linear relationship between voltage and current, which does not hold for all materials and conditions. This assumption is only valid for ohmic materials where resistance remains constant. In reality, many materials and devices exhibit a non-linear behavior where resistance varies with applied voltage or current, rendering Ohm’s law inadequate.
In an Ohm’s law experiment, sources of error can include temperature variations, inaccurate measurement instruments, and contact resistance at the connections. Temperature changes can affect the resistance of the material being tested, leading to inconsistent results. Additionally, any resistance in the connections and measurement inaccuracies can introduce errors in the observed voltage and current values.
Ohm’s law problem refers to the limitation of the law in describing the electrical behavior of non-ohmic materials and complex circuits. It assumes a constant resistance, which is not valid for many real-world materials and devices. This problem highlights the need for more comprehensive models to accurately describe electrical behavior in various contexts.
Ohm’s law is not obeyed under conditions where the material exhibits non-linear current-voltage characteristics, such as in semiconductors, superconductors, and devices like diodes and transistors. High-frequency AC circuits and systems with significant reactance also do not adhere to Ohm’s law. Furthermore, extreme temperatures can cause deviations from Ohm’s law due to changes in material properties.