parallel resistance

Question

Equivalent resistance of R and 2R in parallel is:

RankGuru · Accepted Answer

In a parallel combination, the potential difference ($V$) across all resistors is the same. The total current is the sum of sub-currents:
$I_{total} = \frac{V}{R_1} + \frac{V}{R_2} = V(\frac{1}{R_1} + \frac{1}{R_2})$
$\frac{1}{R_{parallel}} = \frac{1}{R_1} + \frac{1}{R_2} = \frac{1}{R} + \frac{1}{2R} = \frac{3}{2R}$
$R_{parallel} = \frac{2R}{3}$.

Rank Guru

parallel resistance

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