Voltage and Current divider calculations

Certain calculations need you to divide voltage or current among a bunch of resistors.

Voltage division in series

If a voltage $V_{in}$ is being applied to $Z_1$ and $Z_2$ in series,

$$Vdrop_{Z_1} = \frac{Z_1}{Z_1 + Z_2} \times V_{in}$$

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In case of voltage, numerator is the resistance across which we seek the voltage drop.

In case of parallel, each branch gets the full voltage.

Current division in parallel

$$Idrop_{Z_1} = \frac{Z_2}{Z_1+Z_2} \times I_{in}$$

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Use the opposite resistance for numerator.