Distinguish between ohmic and non ohmic substances; explain with the help of example.
Distinguish between ohmic and non ohmic substances; explain with the help of example.
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| Ohmic substances | Non-ohmic substances |
| 1. Substances which obey ohm’s law are called ohmic substances. | Substances which do not obey ohm’s law are called nonohmic substances. |
| 2. Potential difference (V) versus current (I) curve is a straight line. | Potential difference (V) versus current (I) curve is not a straight line. |
| 3. Resistance of these substances is constant i.e. they follow linear I-V characteristic. | Resistance of these substances |
| Expression for resistance is, R = V/I | Expression for resistance is, R = \(lim_{\Delta I \rightarrow 0} \frac{\Delta V}{\Delta I} = \frac{dV}{dI}\) |
| Examples: Gold, silver, copper etc. | Examples: Liquid electrolytes, vacuum tubes, junction diodes, thermistors etc. |
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