This model uses chirp source to test the resonance frequencies of an electrical circuit.

Simulating the model for 10 seconds gives a peak current at 5 seconds:

As the input frequency is swept from 0 to 1000 rad/s during this period, this corresponds to a resonance frequency of 500 rad/s:

This can also be verified by calculating the resonant frequency for the circuit analytically:

Of course for more complicated systems it might be difficult to calculate the resonant frequency analytically, and in these cases a chirp signal can be very useful.

For a step by step tutorial see External Function—Chirp Signal.