Current Electricity — JEE Main PYQs

For a moving coil galvanometer, the deflection in the coil is 0.05 rad when a current of 10 mA is passed through it. If the torsional constant of suspension wire is $4.0\times 10^{-5}\mathrm{Nm}{\mathrm{rad}}^{-1}$, the magnetic field is 0.01 T and the number of turns in the c …

The resistance of a wire is $5\Omega$. It's new resistance in ohm if stretched to 5 times of it's original length will be :

Two cells are connected between points A and B as shown. Cell 1 has emf of 12 V and internal resistance of $3\Omega$. Cell 2 has emf of 6 V and internal resistance of $6\Omega$. An external resistor R of $4\Omega$ is connected across A and B. The current flowing through R will be …

Ratio of thermal energy released in two resistor R and $3R$ connected in parallel in an electric circuit is :

In a metre bridge experiment the balance point is obtained if the gaps are closed by $2\Omega$ and $3\Omega$. A shunt of $X\Omega$ is added to $3\Omega$ resistor to shift the balancing point by 22.5 cm. The value of X is ______

With the help of potentiometer, we can determine the value of emf of a given cell. The sensitivity of the potentiometer is
(A) directly proportional to the length of the potentiometer wire
(B) directly proportional to the potential gradient of the wire
(C) inversely proportional …

When two resistance $R_1$ and $R_2$ connected in series and introduced into the left gap of a meter bridge and a resistance of $10\Omega$ is introduced into the right gap, a null point is found at 60 cm from left side. When $R_1$ and $R_2$ are connected in parallel and i …

A null point is found at 200 cm in potentiometer when cell in secondary circuit is shunted by $5\Omega$. When a resistance of $15\Omega$ is used for shunting null point moves to 300 cm. The internal resistance of the cell is ______ $\Omega$.

The equivalent resistance between A and B is

If the potential difference between B and D is zero, the value of $x$ is $\frac{1}{n}\Omega$. The value of $n$ is ____

The charge flowing in a conductor changes with time as $\mathrm{Q}(\mathrm{t})=\alpha \mathrm{t}-\beta {\mathrm{t}}^2+\gamma {\mathrm{t}}^3$. Where $\alpha ,\beta$ and $\gamma$ are constants. Minimum value of current is :

In the following circuit, the value of $2I_1$ (twice the magnitude of the current $I_1$) is ______ A.

The drift velocity of electrons for a conductor connected in an electrical circuit is $V_d$. The conductor in now replaced by another conductor with same material and same length but double the area of cross section. The applied voltage remains same. The new drift velocity of ele …

Two identical cells, when connected either in parallel or in series gives same current in an external resistance $5\Omega$. The internal resistance of each cell will be $\_\_\_\_$ $\Omega$.

The H amount of thermal energy is developed by a resistor in 10 s when a current of 4A is passed through it. If the current is increased to 16 A, the thermal energy developed by the resistor in 10 s will be:

The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50\%$. The percentage change in voltage sensitivity of the galvanometer will be:

For the given circuit, in the steady state, $|{\mathrm{V}}_{\mathrm{B}}-{\mathrm{V}}_{\mathrm{D}}|=$ ____ V.

Equivalent resistance between the adjacent corners of a regular $n$-sided polygon of uniform wire of resistance R would be:

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: For measuring the potential difference across a resistance of $600\Omega$, the voltmeter with resistance $1000\Omega$ will be preferred over voltmeter with resist …

In the given circuit the value of $\left|\frac{I_1+I_3}{I_2}\right|$ is:

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Alloys such as constantan and manganin are used in making standard resistance coils.

Reason R: Constantan and manganin have very small value of temperature coeffic …

A 1 m long wire is broken into two unequal parts X and Y. The X part of the wire is streched into another wire W. Length of W is twice the length of X and the resistance of W is twice that of Y. Find the ratio of length of X and Y.

A wire of resistance ${\mathrm{R}}_1$ is drawn out so that its length is increased by twice of its original length. The ratio of new resistance to original resistance is:

The current sensitivity of a galvanometer can be increased by :
(A) decreasing the number of turns
(B) increasing the magnetic field
(C) decreasing the area of the coil
(D) decreasing the torsional constant of the spring

Choose the most appropriate answer from the options given …

As shown in the figure, a potentiometer wire of resistance $20\Omega$ and length 300 cm is connected with resistance box (R.B.) and a standard cell of emf 4 V. For a resistance '$R$' of resistance box introduced into the circuit, the null point for a cell of 20 mV is found to be …

Given below are two statements :

Statement I : A uniform wire of resistance $80\Omega$ is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be $5\Omega$.

Statement II : Two resistance 2 R and 3 R are co …

An electrical bulb rated 220 V, 100 W, is connected in series with another bulb rated 220 V, 60 W. If the voltage across combination is 220 V, the power consumed by the 100 W bulb will be about ____ W.

Two sources of equal emfs are connected in series. This combination is connected to an external resistance $R$. The internal resistances of the two sources are $r_1$ and $r_2\left(r_1>r_2\right)$. If the potential difference across the source of internal resistance …

A direct current of 4 A and an alternating current of peak value 4 A flow through resistance of $3\Omega$ and $2\Omega$ respectively. The ratio of heat produced in the two resistances in same interval of time will be :

In meter bridge experiment for measuring unknown resistance 'S', the null point is obtained at a distance 30 cm from the left side as shown at point $D$. If $R$ is $5.6\mathrm{k}\Omega$, then the value of unknown resistance 'S' will be ______ $\Omega$.

A 1 m long copper wire carries a current of 1 A. If the cross section of the wire is $2.0{\mathrm{mm}}^2$ and the resistivity of copper is $1.7\times 10^{-8}\Omega \mathrm{m}$, the force experienced by moving electron in the wire is $\_\_\_\_$ $\times 10^{-23}\mathrm{N}$. …

In the given figure, the value of ${\mathrm{V}}_0$ will be $\_\_\_\_$ V.

Eight copper wire of length $l$ and diameter d are joined in parallel to form a single composite conductor of resistance R . If a single copper wire of length $2l$ have the same resistance ( $R$ ) then its diameter will be $\_\_\_\_$ d.

A battery of 6 V is connected to the circuit as shown below. The current I drawn from the battery is :

A potentiometer wire of length 300 cm is connected in series with a resistance $780\Omega$ and a standard cell of emf 4 V. A constant current flows through potentiometer wire. The length of the null point for cell of emf 20 mV is found to be 60 cm. The resistance of the potentio …

A. The drift velocity of electrons decreases with the increase in the temperature of conductor.
B. The drift velocity is inversely proportional to the area of cross-section of given conductor.
C. The drift velocity does not depend on the applied potential difference to the conduc …

In the given figure of meter bridge experiment, the balancing length AC corresponding to null deflection of the galvanometer is 40 cm. The balancing length, if the radius of the wire AB is doubled, will be ______ cm.

As show in the figure, in steady state, the charge stored in the capacitor is. ______ ×10⁻⁶ C.

A current of 15 mA flows in the circuit as shown in figure. The value of potential difference between the points $A$ and $B$ will be

In a potentiometer arrangement, a cell of emf 1.20 V gives a balance point at 36 cm length of wire. This cell is now replaced by another cell of emf 1.80 V. The difference in balancing length of potentiometer wire in above conditions will be ______ cm.

Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is ______ $\Omega$.

The current I in the given circuit will be :

Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length $l_1$ is 40 cm. Now an unknown resistance x is connected in series with P and new balancing length is found to be 80 cm measured from the same end. Then the value of x will be ____ …

Resistance of the wire is measured as $2\Omega$ and $3\Omega$ at $10^{\circ }\mathrm{C}$ and $30^{\circ }\mathrm{C}$ respectively. Temperature cocoefficient of resistance of the material of the wire is:

All resistances in figure are $1\Omega$ each. The value of current ' I ' is $\frac{\mathrm{a}}{5}\mathrm{A}$. The value of a is ______

The current density in a cylindrical wire of radius $r=4.0$ mm is $1.0\times 10^6$ A/m${}^2$. The current through the outer portion of the wire between radial distances $r/2$ and r is $x\pi$ A; where x is ______.

In the given circuit 'a' is an arbitrary constant. The value of m for which the equivalent circuit resistance is minimum, will be $\sqrt{\frac{x}{2}}$. The value of $x$ is ______.

The cut-off voltage of the diodes (shown in figure) in forward bias is 0.6 V. The current through the resister of $40\Omega$ is ______ mA.

A meter bridge setup is shown in the figure. It is used to determine an unknown resistance R using a given resistor of $15\Omega$. The galvanometer (G) shows null deflection when tapping key is at 43 cm mark from end A. If the end correction for end A is 2 cm, then the determine …

Current measured by the ammeter (A) in the reported circuit when no current flows through $10\Omega$ resistance. will be ____ A.