Which one of the following statements regarding Ohm’s law is not correct ?
Ohm's law is an assumption that current through a conductor is always directly proportional to the potential difference applied to it.
A conducting device obeys Ohm's law when the resistance of a device is independent of magnitude and polarity of applied potential difference.
A conducting material obeys Ohm's law when the resistance of material is independent of the magnitude and direction of applied electric field.
All homogeneous materials obey Ohm's law irrespective of whether the field is within range or strong.
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2019
Statements A, B, and C describe aspects of Ohm’s law or materials obeying it. Statement A describes Ohm’s law as the proportionality between V and I (though the “always” can be debated depending on interpretation, compared to D it’s less definitively wrong). Statements B and C correctly define an ohmic device/material as one whose resistance is independent of the magnitude and direction of the applied potential difference/electric field. Statement D is a universal claim that is false. Many homogeneous materials (e.g., semiconductors, diodes, electrolytes) do *not* obey Ohm’s law. Even ohmic materials like metals can deviate from Ohm’s law at very high electric fields or extreme temperatures.