**R and L in series:**

_{L }is at right angles to V

_{R }then the components are added using pythagoras's theorem, a

^{2}= b

^{2}+ c

^{2}.

The triangle this makes shows the voltages V

_{R}and V

_{L}, and the total voltage V on the hypotenuse (see below).

Since V = IZ, dividing all the sides by I gives R, X

_{L}and Z, the impedances.

Similarly, multiplying all sides by I gives I

^{2}R, I

^{2}X

_{L }and I

^{2}Z , the power dissipated in the components.

The term impedance (Z) is used for the combination of component resistances and reactances, e.g. the 'circuit impedance' refers to the total impedance of a circuit containing a number of resistors, inductors and capacitors whose resistances and reactances have been combined using phasor summation.

**Phase Angle:**

f = cos

^{-1}(R/Z)

**R and C in series:**

R, L and C in series:

This can be visualised from drawing all 3 components on a phasor diagram. The resistance is in phase, therefore it's phasor will be horizontal. The inductance will then have it's phasor going upwards, but the capacitance phasor will come down again from this point. The hypotenuse of the triangle is from the end of the capacitance phasor back to the start. This hypotenuse is the resultant voltage drop.Again, the values can be divided and multiplied by I to give impedance and power respectively.

*V*

^{2}= (V_{R}^{2}+ (V_{L}- V_{C})^{2})Take the square root of these to get the voltage dropped, V.