When a capacitor is added in an LCR circuit , the impedance of the circuit
(a) Decreases
(b) Increases
(c) remain constant
(4) depends on frequency of the AC
Answers
Answer:
Current in a series circuit is the same magnitude and frequency in all elements. So we'll look at voltage using current as the reference.
In an inductor, voltage leads current by 90 degrees. In a capacitor, voltage lags current by 90 degrees. Therefore, the voltages on the inductor and capacitor are 180 degrees out of phase with each other and will then subtract.
So if we can make the voltage drop on the inductor match the voltage drop on the capacitor, then they cancel each other out so the full incoming voltage is dropped across the resistor.
This will only happen at one specific frequency, because for an inductor, reactance goes up with frequency and with a capacitor, reactance goes down with frequency. So at one frequency, their reactance's will be equal, and so the voltage drops across them will be equal in magnitude but 180 degrees out of phase.
This is also known as the resonant frequency.
Answer:
Answer
Correct option is
D
decreases at first, becomes minimum and then increases
We have the formula for Impedance
Z=
R
2
+(X
l
−X
C
)
2
X
C
=
ωC
1
X
l
=ωL
And from the graph it can be easily seen that is Decreases first and then Increases.