Electronics - RLC Circuits and Resonance - Discussion

Discussion Forum : RLC Circuits and Resonance - General Questions (Q.No. 21)
21.
What is the true power consumed in a 30 V series RLC circuit if Z = 20 ohms and R = 10 ohms?
15.0 watts
22.5 watts
30.0 watts
45.0 watts
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
14 comments Page 1 of 2.

Marvin said:   4 years ago
G = Re(Z) = R/Z^2 = 0.025 Ohm;

Active power dissipates only on active resistance (conductivity)
P = U^2G = 30^2 * 0.025 = 22.5 W.
(1)

Satish said:   7 years ago
Thanks @Vishal.

Dhaval pujara said:   8 years ago
Here given,

V = 30v
Z = 20ohms
I = v/z
I=??
Then,
True power(p) = i^2*r.

Simi said:   9 years ago
True power= I^2 * R.
Reactive Power = I^2 * X.
Apparent Power = I^2 * Z.

Here, I = V/Z = 30 / 20 = 3/2.
True power =(3/2)^2 * 10 = 22.5W.
(1)

RAHUL KUSHWAHA said:   9 years ago
@Ram Mohan, your answer is perfectly right. Thanks.

Hriday said:   9 years ago
@Neeraja.

z itself includes r so, do not solve to zt.
z is already given and the z value is used to calculate the current whereas r is used to calculate the power.

Amritpal singh said:   1 decade ago
Then why the answer is not coming by p = I2R = VI = 30*1.5 = 45.

Basitsheikh said:   1 decade ago
@Vishal your answer is very smart and authentic.

Afash said:   1 decade ago
Friends Remember one thing. When the value of Z given in RLC ctk it means that the total R of the circuit is Z. as like:

Z= sqrt of R^2 + (Xl -Xc)^2.
So there is no need to find Resistance of the ckt.

Just like:
I = v/Z.
1.5 A.
Than T.Power = I^2 *R.

So you will get the answer.

Akshay said:   1 decade ago
Circuit current = v/z = 30/20 = 3/2.

True power = vicos (theta).

Where cos (theta) = r/z = 10/20 = 5/10.

True power = 30*3/2*5/10 = 22.5w.


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