Bissoy.com
Doctors Medicines MCQs Q&A

An LCR circuit is connected to AC voltage source V. If VR, VC and VL are the voltage drops across resistance, capacitor and inductor respectively, then V is expressed as:

An LCR circuit is connected to AC voltage source V. If VR, VC and VL are the voltage drops across resistance, capacitor and inductor respectively, then V is expressed as: Correct Answer V = [V<span style="position: relative; line-height: 0; vertical-align: baseline; bottom: -0.25em; font-size:10.5px;">R</span><sup>2</sup><span style="position: relative; line-height: 0; vertical-align: baseline; bottom: -0.25em; font-size:10.5px;"> </span>​+ (V<span style="position: relative; line-height: 0; vertical-align: baseline; bottom: -0.25em; font-size:10.5px;">L</span> - V<sub>C</sub>)<sup>2</sup>]<sup>1/2</sup>

The correct answer is option 3) i.e. V =1/2

CONCEPT:

  • LCR circuit: An electrical circuit constituting an inductor (L), capacitor (C), and resistor (R) connected in series or parallel is called an LCR circuit.
  • For an inductor (L), if we consider the current (I) to be the reference axis, then voltage leads by 90°. For the capacitor (C), the voltage lags by 90°. This is represented by the phasor diagram. ​
    • Phasor diagrams are representations of the voltage(V) - current(I) relationship in AC circuits.
    • A phasor is a vector that rotates about the origin.

EXPLANATION:

From the phasor diagram, voltages VR, VC, and VL are perpendicular to each other.

Using Pythagoras theorem,

V2 = VR2 ​+ (VL - VC)2

⇒ V = 1/2

Related Questions

Ayesha put two drops of oil on the lid of her tiffin box. Next to that, she put two drops of water and two drops of sugar solution. She tilted the lid. She saw some drops slid down quickly, while some were left behind. Which drops slid down her tiffin box the fastest?
Consider the following statement: a) When resistance is connected to the AC source, the current leads the voltage. b) When resistance is connected to the AC source, the current lags behind the voltage. c) When resistance is connected to the AC source, the current and the voltage are in the same phase. Which of the following statement is correct?
An RLC series circuit has a resistance R of 20Ω and a current which lags behind the applied voltage by 45°. If the voltage across the inductor is twice the voltage across the capacitor, the value of inductive resistance is ____________
A 24 Ω resistor, an inductor with a reactance of 120 Ω, and a capacitor with a reactance of 120 Ω are in series across a 60 V source. The circuit is at resonance. The voltage across the inductor is
In ac circuit, resistance 5 ohm is connected with a capacitor having capacitive reactance 12 ohm. Supply of 260 V is connected to the circuit. Calculate the voltage across a capacitor.
What is the source voltage applied across a loop containing a resistor of 1000 ohm and capacitor of 15 microfarads in series when a current of 0.02 ampere flows across the circuit? Given that the voltage drop across capacitor is 5 Volts?
What is the source voltage applied across a loop containing a resistor of 100 ohm and capacitor of 15 microfarads in series when a current of 0.05 ampere flows across the circuit? Given that the voltage drop across capacitor is 2 Volts?
What is the source voltage applied across a loop containing a resistor of 500 ohm and capacitor of 10 microfarads in series when a current of 0.02 ampere flows across the circuit? Given that the voltage drop across capacitor is 2 Volts.
A 330 pF capacitor and a 220 pF capacitor are each connected across a 6 V dc source. The voltage across the 330 pF capacitor is
Consider a capacitor and resistor connected in series to a sinusoidal voltage source. The voltage across the capacitor lags the voltage across the resistor by an angle θ degrees. What is the value of θ?