Ohm’s law does not apply to which of the following ?

Ohm’s law states that the current through a conductor is directly proportional to the potential difference across its ends, provided physical conditions like temperature remain constant [c1][t1]. Materials that follow this linear relationship are termed 'ohmic'. However, semiconductors (such as diodes and transistors) are classified as non-ohmic materials because they exhibit a non-linear current-voltage relationship [t1][t3]. In these materials, resistance varies with the applied voltage or current, violating the constant proportionality required by Ohm's law [t2][t5]. While temperature changes also affect the resistance of conductors, making them behave non-linearly under varying thermal conditions [c1][t1], semiconductors are inherently non-ohmic due to their internal physics and charge carrier dynamics [t1][t4]. Ohm's law remains applicable to AC circuits by using impedance and to conductors under constant temperature [t5].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > What you have learnt > p. 192
2. [2] https://sathee.iitk.ac.in/article/physics/physics-limitations-of-ohms-law/