# Electricity Formulae and Concepts

### Ohm’s law

• Denotes the relationship between voltage (V), current (I) and resistance (R).
• States that voltage across a conductor equals the product of the current and the resistance.

`V = I x R`

### Power in Circuits

• The power (P) generated or consumed in a circuit is the product of the voltage and the current.
• Measured in Watts (W).

`P = V x I`

### Energy Transfer

• Energy (E) transferred in a circuit is the product of power and time.
• Measured in Joules (J).

`E = P x t`

### Resistors in Series

• Total resistance (Rt) of resistors connected in series is the sum of individual resistance values.

`Rt = R1 + R2 + ... + Rn`

### Resistors in Parallel

• For resistors connected in parallel, the reciprocal of total resistance is the sum of reciprocals of individual resistances.

`1/Rt = 1/R1 + 1/R2 + ... + 1/Rn`

### Capacitors in Series

• The reciprocal of total capacitance in a series (Ct) is the sum of the reciprocals of individual capacitances.

`1/Ct = 1/C1 + 1/C2 + ... + 1/Cn`

### Capacitors in Parallel

• Total capacitance of capacitors connected in parallel is the sum of individual capacitance values.

`Ct = C1 + C2 + ... + Cn`