Ohm's law is applicable to

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Question

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ESE Electronics 2020: Official Paper

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DC circuit only
AC circuit only
DC circuit, as well as AC circuit provided account, is taken of the induced emf resulting from the self-inductance of the circuit and the distribution of current in cross-section of the circuit
DC circuit as well as AC circuit provided account is taken of the induced emf resulting from mutual-inductance of the circuit and the distribution of current in cross-section of the circuit

Answer 1

Analysis:

Ohm’s law states that the current flowing through a circuit is proportional to the voltage applied across the circuit.

i.e. I ∝ V

For DC circuits (with only resistance), the above expression becomes:

\(I = \frac{V}{R}\)

R = Resistance of the circuit

For AC circuits (with R, L, and C), the expression becomes:

\(I = \frac{V}{Z}\)

Z = Net impedance of the circuit (including the effect of mutual inductance)

Example:

The net impedance of the circuit will be:

Z = R + jX_net

Where,

X_net = L₁ + L₂ + 2M (since this is series aiding circuit as per the dot convention)

∴ Z = R + j (L₁ + L₂ + 2M)

From Ohm’s law:

\(I = \frac{V}{{R\; + \;j\left( {{L_1}\; + \;{L_2}\; + \;2M} \right)}}\)

∴ We conclude that Ohms law applies to both DC and AC circuits provided that mutual inductance of the circuit is taken into account.