How Does Changing Frequency Affect Current in a Series LC Circuit?

[SimonZ]

Homework Statement

A capacitor and inductor are connected in series to an AC generator. As the generator’s frequency is increased, the current in the capacitor

A. increases

B: decreases

C: does not change

D: can't answer this question due to no enough information.

Homework Equations

The impedance in the LC circuit is Z = │ωL- 1/ωC│
Current I = V/Z

The Attempt at a Solution

If ωL > 1/ωC, then then ω increases, Z also increases, and current will decrease.
If ωL < 1/ωC, then then ω increases, Z decreases, and current will increase.
So the answer to this question is D.

Is the above answer right?

 

[vk6kro]

E: goes up then goes down.
Not a fair question if the right answer is not included.

A series tune circuit becomes low impedance at resonance, so the current goes up when the frequency equals the resonant frequency. Above or below that frequency, the current is less than at resonance.

 

[nlightner]

Yes, your answer is correct. As the frequency increases, the impedance of the circuit also increases, leading to a decrease in current. This is due to the fact that the capacitor's reactance decreases with increasing frequency, while the inductor's reactance increases. The balance of these two reactances determines the overall impedance of the circuit.