How does the sign of the phase angle ϕ , by which the supply voltage leads the current in an LCR series circuit, change as the supply frequency is gradually increased from very low to very high values.

Question

Philoid · Accepted Answer

We know that the phase angle ϕ is given by:

where X_L is inductive reactance, X_C is capacitive reactance and R is resistance.

Note that ϕ is measured is measured from current to voltage.

Now, and where f is frequency.

Initially, frequency is low. Hence, So, ϕ is negative. As frequency increases, we get and . When frequency is high, . Then, ϕ is positive.

How does the sign of the phase angle ϕ, by which the supply voltage leads the current in an LCR series circuit, change as the supply frequency is gradually increased from very low to very high values.