Growth and Decay of Current in a LR Circuit

Author:Asok Kumar Das & Chittaranjan Dasgupta
12th West Bengal Board
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Important Questions on Growth and Decay of Current in a LR Circuit

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An inductor of inductance L=400 mH and resistors of resistances  R1=2 Ω and R2=2 Ω are connected to a battery of emf 12 V as shown in Fig. The internal resistance of the battery is negligible. The switch S is closed at t=0. The potential drop across L as a function of time is

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A coil of inductance 8.4 mH and resistance 6 Ω is connected to a 12 V battery. The current in the coil is 1.0 A at approximately the time 

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A coil of inductance 300 mH and resistance 2 Ω is connected to a source of voltage 2 V. The current reaches half of its steady state value in

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An inductor of 2 H and a resistance of 10 Ω are connected in series with a battery of 5 V. The initial rate of change of current is

 

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An ideal coil of 10 H is connected in series with a resistance of 5 Ω and a battery of 5 V.2 s after the connection is made, the current flowing (in ampere) in the circuit is

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A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant k=2 The level of liquid is d3 initially. Fig. Suppose the liquid level decreases at a constant speed v, the time constant as a function of time is

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What is mean by time-constant of a d.c. circuit with a resistor R and an inductor L connected in series.

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In the R-L series circuit the resistance R=30Ω, reactance XL=40Ω and peak emf E0=220 V. Calculate :

peak current i0 in circuit.

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What is mean by time-constant of a d.c. circuit with a resistor R and an inductor L connected in series.

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Show that both during charging and discharging of a capacitor through a resistance, the current starts with its maximum value and falls off exponentially.

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Establish the equation describing the decay of current in a L-R circuit. Define the time constant for the circuit.

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A steady current is flowing in an electric circuit containing an inductance L and resistance R  in series. All of a sudden the battery is removed from the circuit without breaking the circuit. Explain how current decays smoothly.

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An electric circuit has an inductance L, a resistance R connected in series with a battery of emf ε. Discuss how current grows in the circuit when circuit is switched on. Draw graph to show its variation.

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Write the expression for frequency of an ideal LC circuit. In an actual circuit, why do the oscillations ultimately die away ?