**Complex numbers in electrical engineering**

In mathematics, it is common to denote the imaginary part with the letter i. In electrical engineering, however, the letter i is reserved for the electric current. To avoid confusion, we use j for the imaginary part in the following: Z = x + j y

Examples for the application of the complex numbers in electrical engineering now in the following:

**Example 1: Series connection of R and X**_{l}

What you see is a series connection of an ohmic resistor of 120 Ω and an inductive resistor XL of 80 Ω. Determine mathematically and graphically the complex resistance Z of the series circuit.

Solution:

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