Published by:
CGP EDU Academic Team
Published on: September 12, 2026
A
, F capacitor, a 0.10 H inductor and a
resistor are connected in series with an a.c. source of emf
.
Find (i) the frequency of the emf,
(ii) the reactance of the circuit,
(iii) the impedance of the circuit,
(iv) the current in the circuit and
(v) the phase angle. Also find the effective voltages across the capacitor, inductor and resistor.
Text Solution
Verified by ExpertsThe correct answer is:
A
Given Data:
- Inductance (L) = 0.10 H
- Capacitance (C) = 25.0 μF = 25.0 \times 10^{-6} F
- Resistance (R) = 25.0 Ω
- EMF (E) = 310 sin(314t) V
Step 1: Find the Frequency of the EMF
The angular frequency \( \omega \) is given in the EMF equation: \( E = 310\sin(314t) \).
Therefore, \( \omega = 314 \, ext{rad/s} \)
The frequency (f) can be calculated using the relationship:
\( f = \frac{\omega}{2\pi} = \frac{314}{2\pi} \approx 50 \, ext{Hz} \)
Step 2: Find the Reactance of the Circuit
- Inductive Reactance \( X_L = \omega L = 314 \times 0.10 = 31.4 \, \Omega \)
- Capacitive Reactance \( X_C = \frac{1}{\omega C} = \frac{1}{314 \times 25.0 \times 10^{-6}} \approx 12.74 \, \Omega \)
Step 3: Find the Total Reactance
The total reactance (X) is given by:
\( X = X_L - X_C = 31.4 - 12.74 = 18.66 \, \Omega \)
Step 4: Find the Impedance of the Circuit
The impedance (Z) is given by:
\( Z = \sqrt{R^2 + X^2} = \sqrt{25.0^2 + 18.66^2} \approx 30.29 \, \Omega \)
Step 5: Calculate the Current in the Circuit
From Ohm's law, the current (I) can be found as:
\( I = \frac{E_0}{Z} = \frac{310}{30.29} \approx 10.23 \, A \)
Step 6: Find the Phase Angle
The phase angle (\( \phi \)) can be calculated using:
\( \tan\phi = \frac{X}{R} = \frac{18.66}{25} \Rightarrow \phi = \tan^{-1}\left(\frac{18.66}{25}\right) \approx 38.0^{\circ} \)
Step 7: Find Effective Voltage Across Components
- Voltage across Resistor (V_R): \( V_R = I \cdot R = 10.23 \times 25 \, \approx 255.75 \, V \)
- Voltage across Inductor (V_L): \( V_L = I \cdot X_L = 10.23 \times 31.4 \approx 321.35 \, V \)
- Voltage across Capacitor (V_C): \( V_C = I \cdot X_C = 10.23 \times 12.74 \approx 130.02 \, V \)
Summary:
(i) Frequency = 50 Hz
(ii) Reactance = 18.66 Ω
(iii) Impedance = 30.29 Ω
(iv) Current = 10.23 A
(v) Phase angle = 38.0°
Effective Voltages: V_R ≈ 255.75 V, V_L ≈ 321.35 V, V_C ≈ 130.02 V.
- Inductance (L) = 0.10 H
- Capacitance (C) = 25.0 μF = 25.0 \times 10^{-6} F
- Resistance (R) = 25.0 Ω
- EMF (E) = 310 sin(314t) V
Step 1: Find the Frequency of the EMF
The angular frequency \( \omega \) is given in the EMF equation: \( E = 310\sin(314t) \).
Therefore, \( \omega = 314 \, ext{rad/s} \)
The frequency (f) can be calculated using the relationship:
\( f = \frac{\omega}{2\pi} = \frac{314}{2\pi} \approx 50 \, ext{Hz} \)
Step 2: Find the Reactance of the Circuit
- Inductive Reactance \( X_L = \omega L = 314 \times 0.10 = 31.4 \, \Omega \)
- Capacitive Reactance \( X_C = \frac{1}{\omega C} = \frac{1}{314 \times 25.0 \times 10^{-6}} \approx 12.74 \, \Omega \)
Step 3: Find the Total Reactance
The total reactance (X) is given by:
\( X = X_L - X_C = 31.4 - 12.74 = 18.66 \, \Omega \)
Step 4: Find the Impedance of the Circuit
The impedance (Z) is given by:
\( Z = \sqrt{R^2 + X^2} = \sqrt{25.0^2 + 18.66^2} \approx 30.29 \, \Omega \)
Step 5: Calculate the Current in the Circuit
From Ohm's law, the current (I) can be found as:
\( I = \frac{E_0}{Z} = \frac{310}{30.29} \approx 10.23 \, A \)
Step 6: Find the Phase Angle
The phase angle (\( \phi \)) can be calculated using:
\( \tan\phi = \frac{X}{R} = \frac{18.66}{25} \Rightarrow \phi = \tan^{-1}\left(\frac{18.66}{25}\right) \approx 38.0^{\circ} \)
Step 7: Find Effective Voltage Across Components
- Voltage across Resistor (V_R): \( V_R = I \cdot R = 10.23 \times 25 \, \approx 255.75 \, V \)
- Voltage across Inductor (V_L): \( V_L = I \cdot X_L = 10.23 \times 31.4 \approx 321.35 \, V \)
- Voltage across Capacitor (V_C): \( V_C = I \cdot X_C = 10.23 \times 12.74 \approx 130.02 \, V \)
Summary:
(i) Frequency = 50 Hz
(ii) Reactance = 18.66 Ω
(iii) Impedance = 30.29 Ω
(iv) Current = 10.23 A
(v) Phase angle = 38.0°
Effective Voltages: V_R ≈ 255.75 V, V_L ≈ 321.35 V, V_C ≈ 130.02 V.
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