Current Electricity — JEE Main PYQs

A meter bridge with two resistances $R_1$ and $R_2$ as shown in figure was balanced (null point) at 40 cm from the point P. The null point changed to 50 cm from the point P, when $16\Omega$ resistance is connected in parallel to $R_2$. The values of resistances $R_1$ and $R_2$ ar …

An electric power line having total resistance of $2\Omega$, delivers 1 kW of power of 250 V. The percentage efficiency of transmission line is $\_\_\_\_$.

A cylindrical conductor of length 2 m and area of cross-section $0.2{\mathrm{mm}}^2$ carries an electric current of 1.6 A when its ends are connected to a 2 V battery. Mobility of electrons in the conductor is $\alpha \times 10^{-3}{\mathrm{m}}^2/\mathrm{V}$.s. The value of …

The charge stored by the capacitor C in the given circuit in the steady state is $\_\_\_\_$ $\mu \mathrm{C}$.

The total length of potentiometer wire AB is 50 cm in the arrangement as shown in figure. If P is the point where the galvanometer shows zero reading then the length AP is $\_\_\_\_$ cm .

A battery with EMF E and internal resistance $r$ is connected across a resistance $R$. The power consumption in R will be maximum when :

Two known resistance of $\mathrm{R}\Omega$ and $2\mathrm{R}\Omega$ and and one unknown resistance $\mathrm{X}\Omega$ are connected in a circuit as shown in the figure. If the equivalent resistance between points A and B in the circuit is $\mathrm{X}\Omega$, then the …

A wire of uniform resistance $\lambda \Omega /m$ is bent into a circle of radius r and another piece of wire with length 2r is connected between points A and B (AOB) as shown in figure. The equivalent resistance between points A and B is ______ $\Omega$.

The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at $V_Z=5\text{ V}$ and the desired current in load is 5 mA. The unregulated voltage source can supply upto 25 V. Considering the Zener diode can withstand four times of the load curren …

Two resistors of $100\Omega$ each are connected in series with a 9 V battery. A voltmeter of $400\Omega$ resistance is connected to measure the voltage drop across one of the resistors. The voltmeter reading is ______ V.

Two resistors $2\Omega$ and $3\Omega$ are connected in the gaps of bridge as shown in figure. The null point is obtained with the contact of jockey at some point on wire XY. When an unknown resistor is connected in parallel with $3\Omega$ resistor, the null point is shifted by …

In the potentiometer, when the cell in the secondary circuit is shunted with $4\Omega$ resistance, the balance is obtained at the length 120 cm of wire. Now when the same cell in shunted with $12\Omega$ resistance, the balance is shifted to a length of 180 cm. The internal resi …

Assuming in forward bias condition there is a voltage drop of 0.7 V across a silicon diode, the current through diode ${\mathrm{D}}_1$ in the circuit is ______ mA. (Assume all diodes in the given circuit are identical)

For the two cells having same EMF E and internal resistance $r$, the current passing through the external resistor $6\Omega$ is same when both the cells are connected either in parallel or in series. The value of internal resistance $r$ is ____ $\Omega$.

The equivalent resistance between the points $A$ and $B$ in the following circuit is $\frac{x}{5}\Omega$. The value of $x$ is ____.

The reading of the ammeter (A) in steady state in the following circuit (assuming negligible internal resistance of the ammeter) is ____ A.

A regular hexagon is formed by six wires each of resistance r Ω and the corners are joined to centre by wires of same resistance. If the current enters at one corner and leaves at the opposite corner, the equivalent resistance of the hexagon between the two opposite corners will …

A moving coil galvanometer of resistance 100 Ω shows a full scale deflection for a current of 1 mA. The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of 5 mA, is ____ Ω

In a meter bridge experiment to determine the value of unknown resistance, first the resistances $2\Omega$ and $3\Omega$ are connected in the left and right gaps of the bridge and the null point is obtained at a distance $l\mathrm{cm}$ from the left. Now when an unknown resis …

A wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances $\left(R_1=R_2=R_3=R_4\right)$. When $R_3$ resistance is heated to some temperature, its resistance value has gone up by $10\%$. The potential differenc …

The heat generated in 1 minute between points A and B in the given circuit, when a battery of 9 V with internal resistance of $1\Omega$ is connected across these points is ______ J.

Two resistors of $200\Omega$ and $400\Omega$ are connected in series with a battery of 100 V. A bulb rated at $200\mathrm{V},100\mathrm{W}$ is connected across the $400\Omega$ resistance. The potential drop across the bulb is $\_\_\_\_$ V.

A voltmeter with internal resistance of $x\Omega$ can be used to measure upto 20 V. In order to increase its measuring range to 30 V, the required modification is to ______.

Consider a circuit consisting of a capacitor (20 μF), resistor (100 Ω) and two identical diodes as shown in figure. The resistance of diode under forward biasing condition is 10 Ω. The time constant of the circuit is $\alpha \times 10^{-3}$ s. The value of $\alpha$ is _____ .

The voltage and the current between A and B points shown in the circuit are _____ .

Refer to the figure given below. The values of ${\mathrm{I}}_1$, ${\mathrm{I}}_2$ and ${\mathrm{I}}_3$ are ______.

Refer to the figure given below, current between terminals A and B is ______ A.

Under steady state condition the potential difference across the capacitor in the circuit is ______ V.

When an external resistance of $5\Omega$ is connected across terminals of a cell, a current of 0.25 A flows through it. When the $5\Omega$ resistor is replaced by a $2\Omega$ resistor, a current of 0.5 A flows through it. The internal resistance of the cell is ______ …

The maximum rated power of the LED is 2 mW and it is used in the circuit with input voltage of 5 V as shown in the figure below. The current through resistance ${\mathrm{R}}_{\mathrm{S}}$ is 0.5 mA.

The minimum value of the resistance of $R_s$, to ensure that the LED is not dama …

Refer to the circuit diagram given below. The heat generated across the $6\Omega$ resistance in 100 second is $\frac{\alpha }{100}\mathrm{J}$. The value of $\alpha$ is $\_\_\_\_$. (Nearest integer)

A moving coil of a galvanometer when shunted with $2\Omega$ resistance gives a full scale deflection for a current of 500 mA. When a resistance of $470\Omega$ is connected in series it gives a full scale deflection for 10 V potential applied on it. The value of resistance of ga …

Two cells of emfs 1 V and 2 V and internal resistance $2\Omega$ and $1\Omega$, respectively connected in parallel, gave current of 1 A through an external resistance. If the polarity of one cell is reversed, then value of current through the external resistance will be …

The stored charge in the capacitor in steady state of the following circuit is ______ $\mu \mathrm{C}$.

Sliding contact of a potentiometer is in the middle of the potentiometer wire having resistance $R_p=1\Omega$ as shown in the figure. An external resistance of ${\mathrm{R}}_{\mathrm{e}}=2\Omega$ is connected via the sliding contact.

Given below are two statements:

Statement-I: The equivalent emf of two nonideal batteries connected in parallel is smaller than either of the two emfs.

Statement-II: The equivalent internal resistance of two nonideal batteries connected in parallel is smaller than the internal …

The net current flowing in the given circuit is
______ A.

Identify the valid statements relevant to the given circuit at the instant when the key is closed.
A. There will be no current through resistor $R$.
B. There will be maximum current in the connecting wires.
C. Potential difference between the capacitor plates A and B is minimum. …

Consider a moving coil galvanometer (MCG) :
A : The torsional constant in moving coil galvanometer has dimensions $\left[{\mathrm{ML}}^2{\mathrm{T}}^{-2}\right]$
B : Increasing the current sensitivity may not necessarily increase the voltage sensitivity.
C : If we increase number …

Refer to the circuit diagram given in the figure, which of the following observation are correct?
A. Total resistance of circuit is $6\Omega$.
B. Current in Ammeter is 1 A
C. Potential across AB is 4 Volts.
D. Potential across CD is 4 Volts.
E. Total resistance of the circuit is …

A galvanometer having a coil of resistance $30\Omega$ need 20 mA of current for full-scale deflection. If a maximum current of 3 A is to be measured using this galvanometer, the resistance of the shunt to be added to the galvanometer should be $\frac{30}{\mathrm{X}}\Omega$, whe …

What is the current through the battery in the circuit shown below?

The value of current I in the electrical circuit as given below, when potential at A is equal to the potential at B , will be ______ A.

Find the equivalent resistance between two ends of the following circuit.

A wire of resistance R is bent into an equilateral triangle and an identical wire is bent into a square. The ratio of resistance between the two end points of an edge of the triangle to that of the square is

A wire of resistance $9\Omega$ is bent to form an equilateral triangle. Then the equivalent resistance across any two vertices will be $\_\_\_\_$ ohm.

In a moving coil galvanometer, two moving coils $M_1$ and $M_2$ have the following particulars :
$R_1=5\Omega ,N_1=15,A_1=3.6\times 10^{-3}{\mathrm{m}}^2,B_1=0.25\mathrm{T}$ …

A wire of length 25 m and cross-sectional area 0.5 mm^2 having resistivity of 2 x 10^-6 Ohm m is bent into a complete circle. The resistance between diametrically opposite points will be

In the figure shown below, a resistance of $150.4\Omega$ is connected in series to an ammeter A of resistance $240\Omega$. A shunt resistance of $10\Omega$ is connected in parallel with the ammeter. The reading of the ammeter is ______ mA.

A motor operating on 100 V draws a current of 1 A. If the efficiency of the motor is $91.6\%$, then the loss of power in units of $\text{cal}/\text{s}$ is