Current Electricity — JEE Main PYQs

A capacitor is discharging through a resistor R. Consider in time ${\mathrm{t}}_1$, 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 $t_1/t_2$ will be :

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of $2\Omega$. The value of internal resistance of each cell is :

Two resistors are connected in series across a battery as shown in figure. If a voltmeter of resistance $2000\Omega$ is used to measure the potential difference across $500\Omega$ resister, the reading of the voltmeter will be $\_\_\_\_$ V.

The equivalent resistance between points A and B in the given network is :

Two coils require 20 minutes and 60 minutes respectively to produce same amount of heat energy when connected separately to the same source. If they are connected in parallel arrangement to the same source; the time required to produce same amount of heat by the combination of co …

The variation of applied potential and current flowing through a given wire is shown in figure. The length of wire is 31.4 cm. The diameter of wire is measured as 2.4 cm. The resistivity of the given wire is measured as $x\times 10^{-3}\Omega \mathrm{cm}$. The value of x is __ …

For the network shown below, the value $V_B-V_A$ is ____ V.

An aluminium wire is stretched to make its length, 0.4% larger. Then percentage change in resistance is:

As per the given circuit, the value of current through the battery will be ____ A.

A $72\Omega$ galvanometer is shunted by a resistance of $8\Omega$. The percentage of the total current which passes through the galvanometer is :

A $220\mathrm{V},50\mathrm{Hz}\mathrm{AC}$ source is connected to a 25 V , 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be ____。

A cell, shunted by a $8\Omega$ resistance, is balanced across a potentiometer wire of length 3 m. The balancing length is 2 m when the cell is shunted by $4\Omega$ resistance. The value of internal resistance of the cell will be ______ $\Omega$.

The current density in a cylindrical wire of radius 4 mm is $4\times 10^6{\text{A m}}^{-2}$. The current through the outer portion of the wire between radial distance $\frac{R}{2}$ and R is ______ $\pi \text{A}$.

Two metallic wires of identical dimensions are connected is series. If ${\sigma }_1$ and ${\sigma }_2$ are the conductivities of the these wires respectively, the effective conductivity of the combination is:

The current I flowing through the given circuit will be ______ A.

Two identical cells each of emf 1.5 V are connected in parallel across a parallel combination of two resistors each of resistance $20\Omega$. A voltmeter connected in the circuit measures 1.2 V . The internal resistance of each cell is

In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is $3:2$, the difference in the balancing length of the potentiometer wire in abov …

What will be the most suitable combination of three resistors $A=2\Omega$, $B=4\Omega$, $C=6\Omega$ so that $\left(\frac{22}{3}\right)\Omega$ is equivalent resistance of combination?

A potentiometer wire of length 10 m and resistance $20\Omega$ is connected in series with a 25 V battery and an external resistance $30\Omega$. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E (in volt) is $\frac{x}{10}$. The va …

In the given circuit- the value of current ${\mathrm{I}}_{\mathrm{L}}$ will be $\_\_\_\_$ mA.
(When ${\mathrm{R}}_{\mathrm{L}}=1\mathrm{k}\Omega$)

Two cells of same emf but different internal resistances $r_1$ and $r_2$ are connected in series with a resistance $R$. The value of resistance $R$, for which the potential difference across second cell is zero, is

If n represents the actual number of deflections in a converted galvanometer of resistance G and shunt resistance S. Then the total current I when its figure of merit is K will be:

The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be $\_\_\_\_$ %.

A teacher in his physics laboratory allotted an experiment to determine the resistance (G) of a galvanometer. Students took the observations for $\frac{1}{3}$ deflection in the galvanometer. Which of the below is true for measuring value of $G$?

A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is ______ J.

The total current supplied to the circuit as shown in figure by the 5 V battery is ______ A

In the given figure, the emf of the cell is 2.2 V and if internal resistance is $0.6\Omega$. Calculate the power dissipated in the whole circuit :

What equal length of an iron wire and a copper-nickel alloy wire, each of 2 mm diameter connected parallel to give an equivalent resistance of $3\Omega$?
(Given resistivities of iron and copper-nickel alloy wire are $12\mu \Omega \mathrm{cm}$ and $51\mu \Omega \mathrm{cm}$ r …

A cell ${\mathrm{E}}_1$ of emf 6 V and internal resistance $2\Omega$ is connected with another cell ${\mathrm{E}}_2$ of emf 4 V and internal resistance $8\Omega$ (as shown in the figure). The potential difference across points $X$ and $Y$ is:

A current through a wire depends on time as
$i={\alpha }_{0}t+\beta t^2$
Where ${\alpha }_0=20\mathrm{A}/\mathrm{s}$ and $\beta =8A{s}^{-2}$. Find the charge crossed through a section of the wire in 15s.

An electric bulb of 500 watt at 100 volt is used in a circuit having a 200 V supply. Calculate the resistance R to be connected in series with the bulb so that the power delivered by the bulb is 500 W.

If you are provided a set of resistances $2\Omega ,4\Omega ,6\Omega$ and $8\Omega$. Connect these resistances so as to obtain an equivalent resistance of $\frac{46}{3}\Omega$.

The value of current in the $6\Omega$ resistance is :

For the circuit shown below, calculate the value of ${\mathrm{I}}_2$ :

A current of 5 A is passing through a non-linear magnesium wire of cross-section $0.04{\mathrm{m}}^2$. At every point the direction of current density is at an angle of $60^{\circ }$ with unit vector of area of cross-section. The magnitude of electric field at every point of the …

A cylindrical wire of radius 0.5 mm and conductivity $5\times 10^7\mathrm{S}/\mathrm{m}$ is subjected to an electric field of $10\mathrm{mV}/\mathrm{m}$. The expected value of current in the wire will be $x^3\pi \mathrm{mA}$. The value of $x$ is
____

In the given figure switches ${\mathrm{S}}_1$ and ${\mathrm{S}}_2$ are in open condition. The resistance across ab when the switches ${\mathrm{S}}_1$ and ${\mathrm{S}}_2$ are closed is ____ $\Omega$.

The colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is :

For full scale deflection of total 50 divisions, 50 mV voltage is required in galvanometer. The resistance of galvanometer if its current sensitivity is 2 div/mA will be :

The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is $x:8$. The value of $x$ is ____.

A Copper( Cu ) rod of length 25 cm and cross sectional area $3{\mathrm{mm}}^2$ is joined with a similar aluminium(AI)rod as shown in figure. Find the resistance of the combination between the ends $A$ and B .
(Take Resistivity of Copper $=1.7\times 10^{-8}\Omega \mathrm{m}$ …

In an electric circuit, a cell of certain emf provides a potential difference of 1.25 V across a load resistance of $5\Omega$. However, it provides a potential difference of 1 V across a load resistance of $2\Omega$. The emf of the cell is given by $\frac{x}{10}\mathrm{V}$. T …

Five equal resistances are connected in a network as shown in figure. The net resistance between the points $A$ and $B$ is :

The circuit contains two diodes each with a forward resistance of $50\Omega$ and with infinite reverse resistance. If the battery voltage is 6 V , the current through the $120\Omega$ resistance is ____ m A.

In an electrical circuit, a battery is connected to pass 20 C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at 15 V . The work done by the battery is ____ J.

Five identical cells each of internal resistance $1\Omega$ and emf 5 V are connected in series and in parallel with an external resistance ' R '. For what value of ' R ', current in series and parallel combination will remain the same?

A circuit is arranged as shown in figure. The output voltage $V_O$ is equal to ______ V.

First, a set of n equal resistors of $10\Omega$ each are connected in series to a battery of emf 20 V and internal resistance $10\Omega$. A current I is observed to flow. Then, the n resistors are connected in parallel to the same battery. It is observed that the current is inc …

A wire of $1\Omega$ has a length of 1 m. It is stretched till its length increases by $25\%$. The percentage change in resistance to the nearest integer is:

The equivalent resistance of the given circuit between the terminals $A$ and $B$ is :