Advertisements
Advertisements
Question
When an alternating voltage of 220V is applied across device X, a current of 0.25A flows which lags behind the applied voltage in phase by π/2 radian. If the same voltage is applied across another device Y, the same current flows but now it is in phase with the applied voltage.
- Name the devices X and Y.
- Calculate the current flowing in the circuit when the same voltage is applied across the series combination of X and Y.
Advertisements
Solution
(i) In device X, the Current lags behind the voltage by π/2, X is an inductor.
In device Y, Current in phase with the applied voltage, and Y is resistor.
(ii) We are given that,
Current = `"V"/"X"_"L"`
Or, `0.25 = 220/"X"_"L"`,
∴ XL = 880Ω
Again, Current = `"V"/"R"`
Or, `0.25 = 220/"R"`
∴ R = 880Ω
For the series combination of X and Y,
Equivalent impedance Z = `sqrt(880^2 + 880^2)`
Z = `880sqrt2Omega`
Current = `"V"/"Z"`
Or, I = `220/(880sqrt2)`
∴ I = 0.177 A
APPEARS IN
RELATED QUESTIONS
In a series LCR circuit, obtain the condition under which watt-less current flows in the circuit ?
Answer the following question.
What is the phase difference between the voltages across the inductor and the capacitor at resonance in the LCR circuit?
Answer the following question.
Draw the diagram of a device that is used to decrease high ac voltage into a low ac voltage and state its working principle. Write four sources of energy loss in this device.
Use the expression for Lorentz force acting on the charge carriers of a conductor to obtain the expression for the induced emf across the conductor of length l moving with velocity v through a magnetic field B acting perpendicular to its length.
The selectivity of a series LCR a.c. circuit is large, when ______.
Choose the correct answer from given options
The phase difference between the current and the voltage in series LCR circuit at resonance is
A series LCR circuit with L = 0.12 H, C = 480 nF, R = 23 Ω is connected to a 230 V variable frequency supply.
(a) What is the source frequency for which current amplitude is maximum. Obtain this maximum value.
(b) What is the source frequency for which average power absorbed by the circuit is maximum. Obtain the value of this maximum power.
(c) For which frequencies of the source is the power transferred to the circuit half the power at resonant frequency? What is the current amplitude at these frequencies?
(d) What is the Q-factor of the given circuit?
If the rms current in a 50 Hz ac circuit is 5 A, the value of the current 1/300 seconds after its value becomes zero is ______.
An alternating voltage of 220 V is applied across a device X. A current of 0.22 A flows in the circuit and it lags behind the applied voltage in phase by π/2 radian. When the same voltage is applied across another device Y, the current in the circuit remains the same and it is in phase with the applied voltage.
- Name the devices X and Y and,
- Calculate the current flowing in the circuit when the same voltage is applied across the series combination of X and Y.
A series LCR circuit is connected to an ac source. Using the phasor diagram, derive the expression for the impedance of the circuit.
