Question

Why we find high resistance experimentally through leakage method or discharge method, although we can also use Ohm's law. Please explain it in detail the advantages if exist.

Answer 1

The resistances present inside a multimeter or voltmeter are very high, but when we are presented with a circuit with even higher or comparable resistances, the circuitry of these instruments will fail to output a reliable measurement due to Loading Effect. Loading effect causes some finite voltage drop across the current element which will be deducted from the output reading, giving us a false value of voltage, which is lesser than the true value.

This is practical difficulty rather than a theoretical one, therefore to alleviate the problem of using a specially designed voltmeter, we can use Leakage method if we ever want to measure very high resistances.