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Ohm's law

Basic electrical relations, LED bias, passive networks and matched or unmatched Pi/T attenuators.

Inputs

Choose a calculator and enter the values.

Calculator
E-I-R
V
A
Ω

Result

Enter your values to calculate a result.

Voltage, current and resistance
Voltage, current and resistance

Voltage drives current through a resistance. Choose the quantity you want to calculate, then enter the other two. The same page also includes LED resistors, passive networks and attenuators.

Illustration only. Not to scale.

Voltage

N/A

N/AN/A
N/AN/A
N/AN/A
N/AN/A
Method and assumptions

Ideal components only. Ohm's law uses V = IR and P = VI. Series and parallel networks use the usual component equations.

Pi and T attenuators use the standard two-port relations. For a matched pad, both ports have the same impedance. For an unmatched pad, enter Zin and Zout separately.

  • Resistor power is calculated for the entered voltage.
  • Capacitor and inductor networks ignore ESR, DCR and self-resonance.
  • The attenuator results are ideal resistor values. Choose suitable E-series values, then check the response again.

Choose a calculation and enter the known values

For E-I-R, choose the quantity to solve and enter the other two. For a resistor network, enter the applied voltage to get total current and power as well as the combined resistance.