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Define Impedance. - Physics

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प्रश्न

Define Impedance.

परिभाषा
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उत्तर

The effective opposition offered by the inductor, capacitor and resistor connected in series to flow of AC current. is called impedance.

Z = `sqrt("R"^2 + (Χ_"L" - Χ_"C")^2)`

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2021-2022 (March) Set 1

संबंधित प्रश्न

In a series LCR circuit, VL = VC ≠ VR. What is the value of power factor?


A series LCR circuit is connected across an a.c. source of variable angular frequency 'ω'. Plot a graph showing variation of current 'i' as a function of 'ω' for two resistances R1 and R2 (R1 > R2).

Answer the following questions using this graph :

(a) In which case is the resonance sharper and why?

(b) In which case in the power dissipation more and why?


A voltage V = V0 sin ωt is applied to a series LCR circuit. Derive the expression for the average power dissipated over a cycle. Under what condition (i) no power is dissipated even though the current flows through the circuit, (ii) maximum power is dissipated in the circuit?


(i) Find the value of the phase difference between the current and the voltage in the series LCR circuit shown below. Which one leads in phase : current or voltage ?

(ii) Without making any other change, find the value of the additional capacitor C1, to be connected in parallel with the capacitor C, in order to make the power factor of the circuit unity.


The figure shows a series LCR circuit with L = 10.0 H, C = 40 μF, R = 60 Ω connected to a variable frequency 240 V source, calculate

(i) the angular frequency of the source which drives the circuit at resonance,

(ii) the current at the resonating frequency,

(iii) the rms potential drop across the inductor at resonance.


Show that in an a.c. circuit containing a pure inductor, the voltage is ahead of current by π/2 in phase ?


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A solenoid having inductance 4.0 H and resistance 10 Ω is connected to a 4.0 V battery at t = 0. Find (a) the time constant, (b) the time elapsed before the current reaches 0.63 of its steady-state value, (c) the power delivered by the battery at this instant and (d) the power dissipated in Joule heating at this instant.


The magnetic field at a point inside a 2.0 mH inductor-coil becomes 0.80 of its maximum value in 20 µs when the inductor is joined to a battery. Find the resistance of the circuit.


(i) An a.c. source of emf ε = 200 sin omegat is connected to a resistor of 50 Ω . calculate : 

(1) Average current (`"I"_("avg")`)

(2) Root mean square (rms) value of emf 

(ii) State any two characteristics of resonance in an LCR series circuit. 


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Draw a labelled graph showing a variation of impedance of a series LCR circuit with frequency of the a.c. supply.


Answer the following question.
In a series LCR circuit connected across an ac source of variable frequency, obtain the expression for its impedance and draw a plot showing its variation with frequency of the ac source. 


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Derive an expression for the average power dissipated in a series LCR circuit.


In series combination of R, L and C with an A.C. source at resonance, if R = 20 ohm, then impedence Z of the combination is ______.


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At resonance frequency the impedance in series LCR circuit is ______.


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Which of the following components of an LCR circuit, with a.c. supply, dissipates energy?


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  2. Interpret each term physically.
  3. Cast the equation in the form of a conservation of energy statement.
  4. Integrate the equation over one cycle to find that the phase difference between v and i must be acute.

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  1. Name the devices X and Y and,
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Select the most appropriate option with regard to resonance in a series LCR circuit.


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