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Diagram shows an uncharged capacitor connected in series with a resistor $R$ and an ideal battery. At $t = 0$ , switch $S_{w}$ is closed and it is observed that, when charge on capacitor is $75 %$ of the maximum value then, current in the circuit is $1 A$ . The value of $R$ is:

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Important Questions on Current Electricity

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

An $R C$ circuit as shown in the figure is driven by a $A C$ source generating a square wave. The output wave pattern monitored by $C R O$ would look close to :

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

Determine the charge on the capacitor in the following circuit:
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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

For the given input voltage waveform $V_{in} (t),$ the output voltage waveform $V_{0} (t),$ across the capacitor is correctly depicted by :

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

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A capacitor of capacitance $C = 1 μ F$ is suddenly connected to a battery of $100 V$ through a resistance $R = 100 Ω .$ The time taken for the capacitor to be charged to get $50 V$ is:

(Take $\ln 2 = 0.69$ )

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

In the given circuit diagram, when the current reaches a steady-state in the circuit, the charge on the capacitor of capacitance

C

will be:

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

A parallel plate capacitor (of capacitance

C)

with circular plates of radius

r_{0}

located at position

\pm α,

is connected in series with a resistor

R

and is charged by a battery of voltage

V .

Consider a circular loop

L

of radius

\underline{r_{0}}

parallel to the capacitor plates is located at

\bar{2}

the center. Which of the following statements is correct ?

HARD

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

Two identical capacitors

A

and

B,

charged to the same potential

5 V

are connected in two different circuits as shown below at time

t = 0 .

If the charge on capacitors

A

and

B

at time

t = C R

Q_{A}

and

Q_{B}

respectively, then (Here

e

is the base of natural logarithm)

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

The circuit shown in the figure consists of a charged capacitor of capacity $3 μ F$ and a charge of $30 μ C .$ At time $t = 0,$ when the key is closed, the value of current flowing through the $5 M Ω$ resistor is $x μA .$ The value of $x$ to the nearest integer is

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

Consider the circuit shown in the figure below:

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All the resistors are identical. The charge stored in the capacitor, once it is fully charged, is

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

A blackbox $(B B)$ which may contain a combination of electrical circuit elements (resistor, capacitor or inductor) is connected with other external circuit elements as shown below in the figure $(a)$ . After the switch $(S)$ is closed at time $t = 0$ , the current $(I)$ as a function of time $(t)$ is shown in the figure $(b)$ .

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From this we can infer that the black-box contains

EASY

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

Tbe dimension of

1 / R C

, where

R

is the resistance and

C

is the capacitance, is the same as that of

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

In an

LCR

circuit as shown below both switches are open initially. Now switch

S_{1}

is closed,

S_{2}

kept open. (

q

is charge on the capacitor and

τ = RC

is capacitive time constant). Which of the following statement is correct?
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EASY

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

L, C

and

R

represent the quantities inductance, capacitance and resistance respectively. The combination which has the dimensions of frequency is

EASY

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

What is the charge on the capacitor in the circuit shown below?

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HARD

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

A capacitor is discharging through a resistor

R

. Consider in time

t_{1}

, the energy stored in the capacitor reduces to half of its initial value and in time

t_{2}

, the charge stored reduces to one eighth of its initial value. The ratio

\frac{t_{1}}{t_{2}}

will be

HARD

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

In the circuit shown below, the key is pressed at time $t = 0$ . Which of the following statement(s) is(are) true?
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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

A capacitor of

50 μ F

is connected in a circuit as shown in figure. The charge on the upper plate of the capacitor is _________

μ C .

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

The circuit shown has been connected for a long time. The voltage across the capacitor is,

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Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

In the given circuits

(a)

and

(b)

, switches

S_{1}

and

S_{2}

are closed at

t = 0

and kept close for a long time. The variation of currents in the two circuits for

t \geq 0

are shown in the options. (Figures are schematic and not drawn to scale.)
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HARD

Physics>Electricity and Magnetism>Current Electricity>RC Circuit with DC Source

An infinite line charge of uniform electric charge density

λ

lies along the axis of an electrically conducting infinite cylindrical shell of radius R. At time t = 0, the space inside the cylinder is filled with a material of permittivity

ε

and electrical conductivity

σ

. The electrical conduction in the material follows Ohm's law. Which one of the following graphs best describes the subsequent variation of the magnitude of current density j(t) at any point in the material?

Diagram shows an uncharged capacitor connected in series with a resistor R and an ideal battery. At t=0, switch Sw is closed and it is observed that, when charge on capacitor is 75% of the maximum value then, current in the circuit is 1 A. The value of R is:

Important Questions on Current Electricity

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Diagram shows an uncharged capacitor connected in series with a resistor $R$ and an ideal battery. At $t = 0$ , switch $S_{w}$ is closed and it is observed that, when charge on capacitor is $75 %$ of the maximum value then, current in the circuit is $1 A$ . The value of $R$ is: