What is a series resonance circuit?

Hint: In the question, we are asked to explain what a series resonance circuit is. Firstly, identify the circuit of which we are talking about. Then, think of the conditions that are used to define a series resonance circuit. Also, give a brief note on resonant frequency.

Complete answer:
In the question we are asked to explain what a series resonance circuit is. When we talk about a series resonance circuit, what has to come to your mind is that of the series RLC circuit. Whenever the circuit current is seen to be in phase with the circuit voltage, then we could say that the particular circuit is in series resonance. Another condition used to define series resonance in an RLC circuit is that the inductive reactance would be equal to that of the capacitive reactance.
One should also know that a series resonant circuit is known to have the ability so as to absorb heavy current as well as power from the mains.
Now, at resonance we have,
${{X}_{L}}={{X}_{C}}$……………………………………… (1)
Now, we have the impedance as,
$Z=\sqrt{{{R}^{2}}+{{\left( {{X}_{L}}-{{X}_{C}} \right)}^{2}}}$
From (1) we have,
$Z=R$
Thereby, we could now conclude that, for a circuit under resonance, the sole source of opposition to current flow would be that due to resistance and hence will draw maximum current.
Note: The frequency at which resonance occurs is known to be resonance frequency. We could derive the expression for resonance frequency from (1).
$2\pi fL=\dfrac{1}{2\pi fC}$
$\therefore f=\dfrac{1}{2\pi \sqrt{LC}}$
These circuits fall under the most important circuits in electrical and electronic circuits.