| Volts (V) |
$E~or~V=W/Q$ |
electromotive force EMF or potential diff. PD = work [J] / charge [C] |
| Ohms (Ω) |
$R=V/I$ |
resistance = voltage [V] / current [A] |
| Volts (V) |
$V=I*R$ |
voltage = current [A] x resistance [Ω] |
| Watts (W) |
$P=I*V$ |
electrical power = current [A] x voltage [V] |
| Joules (J) |
$E=P*t$ |
electrical energy (1) = power [W] x time [s] |
| Joules (J) |
$E=IVt$ |
electrical energy (1) = current [A] x p.d. [V] x time [s] |
| kWh |
$E=P*t$ |
electrical energy (2) = power [kW] x time [h] |
| Volts (V) |
$V_1\;+ V_2\;+ V_3...V_n$ |
total voltage (emf) in simple circuit = voltage_1 + voltage_2 + voltage_3… |
| Ohms (Ω) |
$R_1\;+ R_2\;+ R_3...R_n$ |
total resistance in simple circuit = resistance_1 + resistance_2… |
| Ohms (Ω) |
$\frac{1}{R_1}\;+ \frac{1}{R_2}\;+ \frac{1}{R_3}... \frac{1}{R_n}$ |
total resistance in parallel circuit = 1 / resistance_1 + 1 / resistance_2… |
|
$\frac{V_1}{V_2}=\frac{R_1}{R_2}$ |
potential divider (same ratio equation) |
|
$\frac{V_p}{V_s} = \frac{N_p}{N_s}$ |
transformers: primary voltage [V] / secondary voltage [V] = |
| number of coils turn in primary / number of coils turn in secondary |
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$P_{input}=P_{output}$ |
full efficient transformers: power input [W] = power output [W] |
|
$I_p \times V_p = I_s \times V_s$ |
full efficient transformers: primary current [A] x primary voltage [V] = secondary current [A] x secondary voltage [V] |
| Watts (W) |
$P_{loss} = I^2 \times \Omega$ |
power loss = current² [A] x resistance [Ω] |