write down the limitation of ohms law?
Answers
LIMITATION OF OHMS LAW
1.There is a range of voltages over which the resistance is fairly constant. Due to dissipation of heat, the resistance is heated and its resistance changes.
2. The resistance does not obey near the breakdown voltage of the materials. The materials become super conductors at very high voltages.
3. Some materials do not obey ohm's law below a certain temperature. the material behaves differently.
4. Ohmic resistors only follow ohm’s law. Non-ohmic resistors like diodes, semi-conductors or insulators, do not obey ohm’s law.
5. Resistance depends on the temperature. It increases with temperature.
6. Resistance is also altered, there is a presence of magnetic field or electric field, if that induces an emf in the conductor. That is, if there is an electromagnetic effect.
7. Every real conductor or resistor has an inherent capacitance and inductance. That could depend on the geometrical shapes too. It is not a pure resistance.
8. For gases and liquids, the law is perhaps not valid exactly. For ionic substances, the law may be invalid exactly.
for finding a correct resistance the temperature of conductor should not change
when R increases V also increases but when I increases R decreases