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In a series LCR circuit, voltage applied...

In a series LCR circuit, voltage applied is `V=3sin(314t+(pi)/(6))` and current from the supply is `l=2sin(315t+(pi)/(3))`. Which of the following is correct ?

A

Impendance of circuit is `1.5Omega`

B

Reactance of circuit is `(4)/(3)Omega`

C

Resistance of circuit is `(3sqrt3)/(4)Omega`

D

Wattless component of current is `(1)/(sqrt2)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given voltage and current equations in the LCR circuit and determine which statements about the circuit are correct. ### Given: - Voltage: \( V = 3 \sin(314t + \frac{\pi}{6}) \) - Current: \( I = 2 \sin(315t + \frac{\pi}{3}) \) ### Step 1: Identify the parameters from the voltage and current equations. From the voltage equation: - Amplitude of voltage, \( V_0 = 3 \) - Angular frequency of voltage, \( \omega_v = 314 \) - Phase angle of voltage, \( \phi_v = \frac{\pi}{6} \) From the current equation: - Amplitude of current, \( I_0 = 2 \) - Angular frequency of current, \( \omega_i = 315 \) - Phase angle of current, \( \phi_i = \frac{\pi}{3} \) ### Step 2: Calculate the impedance of the circuit. In a series LCR circuit, the impedance \( Z \) can be calculated using the formula: \[ Z = \frac{V_0}{I_0} \] Substituting the values we have: \[ Z = \frac{3}{2} = 1.5 \, \text{ohm} \] ### Step 3: Determine the reactance of the circuit. The reactance \( X \) in a series LCR circuit can be calculated using: \[ X_L = \omega L \quad \text{and} \quad X_C = \frac{1}{\omega C} \] However, we do not have the values of \( L \) and \( C \) provided in the problem, so we cannot calculate the reactance directly. Thus, we cannot confirm the reactance statement. ### Step 4: Calculate the average power in the circuit. The average power \( P \) in the circuit can be calculated using: \[ P = V_{rms} \cdot I_{rms} \cdot \cos(\delta \phi) \] Where \( \delta \phi = \phi_i - \phi_v \): \[ \delta \phi = \frac{\pi}{3} - \frac{\pi}{6} = \frac{\pi}{6} \] Calculating \( V_{rms} \) and \( I_{rms} \): \[ V_{rms} = \frac{V_0}{\sqrt{2}} = \frac{3}{\sqrt{2}}, \quad I_{rms} = \frac{I_0}{\sqrt{2}} = \frac{2}{\sqrt{2}} = \sqrt{2} \] Now substituting into the power formula: \[ P = \left(\frac{3}{\sqrt{2}}\right) \cdot \left(\sqrt{2}\right) \cdot \cos\left(\frac{\pi}{6}\right) \] \[ P = 3 \cdot \frac{\sqrt{3}}{2} = \frac{3\sqrt{3}}{2} \] ### Step 5: Calculate the resistance of the circuit. Using the relationship between power and resistance: \[ P = I_{rms}^2 \cdot R \] Substituting \( I_{rms} = \sqrt{2} \): \[ \frac{3\sqrt{3}}{2} = (\sqrt{2})^2 \cdot R \] \[ \frac{3\sqrt{3}}{2} = 2R \implies R = \frac{3\sqrt{3}}{4} \, \text{ohm} \] ### Step 6: Calculate the wattless component of current. The wattless component of current is given by: \[ I_{wattless} = I_{rms} \cdot \cos(\phi_i) \] Substituting \( I_{rms} = \sqrt{2} \) and \( \phi_i = \frac{\pi}{3} \): \[ I_{wattless} = \sqrt{2} \cdot \cos\left(\frac{\pi}{3}\right) = \sqrt{2} \cdot \frac{1}{2} = \frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}} \] ### Summary of Results: 1. Impedance \( Z = 1.5 \, \text{ohm} \) (Correct) 2. Reactance cannot be determined (Incorrect) 3. Resistance \( R = \frac{3\sqrt{3}}{4} \, \text{ohm} \) (Correct) 4. Wattless component of current \( = \frac{1}{\sqrt{2}} \) (Correct) ### Final Answer: - The correct statements are: - Impedance of the circuit is \( 1.5 \, \text{ohm} \). - Resistance of the circuit is \( \frac{3\sqrt{3}}{4} \, \text{ohm} \). - Wattless component of current is \( \frac{1}{\sqrt{2}} \).
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