Current Electricity

Electrons drift with speed \({\mathrm{v}}_{\mathrm{d}}\) in a conductor with potential difference V across its ends. If V is reduced to \(\left(\frac{\mathrm{V}}{2}\right)\), their drift speed will become :

In a uniform straight wire, conduction electrons move along +x direction.
Let \(\vec{E}\) and \(\vec{j}\) be the electric field and current density in the wire, respectively. Then :

In a uniform straight wire, conduction electrons move along +x direction.
Let \(\vec{E}\) and \(\vec{j}\) be the electric field and current density in the wire, respectively. Then :

The resistance of a wire of length L and radius r in R. Which one of the following would provide a wire of the name material of resistance \(\frac{R}{2}\) ?

Electrons drift with speed \({\mathrm{v}}_{\mathrm{d}}\) in a conductor with potential difference V across its ends. If V is reduced to \(\left(\frac{\mathrm{V}}{2}\right)\), their drift speed will become :

Two wires P and Q are made of the same material. The wire Q has twice the diameter and half the length as that of wire P. If the resistance of wire P is R, the resistance of the wire Q will be

Given below are two statements :
Statement-I: The equivalent emf of two nonideal batteries connected in parallel is smaller than either of the two emis.
Statement-II : The equivalent internal resistance of two nonideal batteries connected in parallel is smaller than the internal resistance of either of the two batteries.
In the light of the above statements, choose the correct answer from the options given below.

[JEE Main 2025, 22 Jan (Shift 1)]

A moving coil galvanometer with coil resistance \(G=30\text{ }\Omega\), shows full-scale deflection when the current through it is \(20\text{ }\text{mA}\). The galvanometer is converted to an ammeter of range \(3\text{ }\text{A}\) by using a shunt resistance \(S\). The resistance \(S\) is:

Two wires P and Q are made of the same material. The wire Q has twice the diameter and half the length as that of wire P. If the resistance of wire P is R, the resistance of the wire Q will be

Statement I: When non-ideal batteries are connected in parallel, the resultant EMF is less than either of the batteries.

Statement II: When non-ideal batteries are connected in parallel, the resultant resistance of their internal resistances is smaller than either of the individual resistances.

Choose the correct option which is given below:(JEE Mains - 21 Jan 2025 - Shift I Memory Based)

A wire of resistance \(9\text{ }\Omega\) is bent into the shape of an equilateral triangle. What is the equivalent resistance between any two vertices of the triangle?

(Shift I Memory Based)

Electrons drift with speed \({\mathrm{v}}_{\mathrm{d}}\) in a conductor with potential difference V across its ends. If V is reduced to \(\left(\frac{\mathrm{V}}{2}\right)\), their drift speed will become :

A battery supplies 0.9 A current through a \(2\Omega\) resistor and 0.3 A current through a \(7\Omega\) resistor when connected one by one. The internal resistance of the battery is :

The resistance of a wire of length L and radius r in R. Which one of the following would provide a wire of the name material of resistance \(\frac{R}{2}\) ?

In a uniform straight wire, conduction electrons move along +x direction.
Let \(\vec{E}\) and \(\vec{j}\) be the electric field and current density in the wire, respectively. Then :

A wire of resistance \(9\text{ }\Omega\) is bent into the shape of an equilateral triangle. What is the equivalent resistance between any two vertices of the triangle?

(Shift I Memory Based)

In a metre-bridge when a resistance in the left gap is \(2 \Omega\) and unknown resistance in the right gap, the balance length is found to be \(40\) cm. On shunting the unknown resistance with \(2 \Omega\), the balance length changes by:EndFragment

The resistance of a wire of length L and radius r in R. Which one of the following would provide a wire of the name material of resistance \(\frac{R}{2}\) ?

The resistance of a wire of length L and radius r in R. Which one of the following would provide a wire of the name material of resistance \(\frac{R}{2}\) ?

Electrons drift with speed \({\mathrm{v}}_{\mathrm{d}}\) in a conductor with potential difference V across its ends. If V is reduced to \(\left(\frac{\mathrm{V}}{2}\right)\), their drift speed will become :

In a uniform straight wire, conduction electrons move along +x direction.
Let \(\vec{E}\) and \(\vec{j}\) be the electric field and current density in the wire, respectively. Then :

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 \(\frac{30}{X}\Omega\), where\(X\) is

[JEE Main 2025, 23 Jan (Shift 2)]

A battery supplies 0.9 A current through a \(2\Omega\) resistor and 0.3 A current through a \(7\Omega\) resistor when connected one by one. The internal resistance of the battery is :

Two wires P and Q are made of the same material. The wire Q has twice the diameter and half the length as that of wire P. If the resistance of wire P is R, the resistance of the wire Q will be

A battery supplies 0.9 A current through a \(2\Omega\) resistor and 0.3 A current through a \(7\Omega\) resistor when connected one by one. The internal resistance of the battery is :

The potential difference across a cell in an open circuit is \(8 V\). It falls to \(4 V\) when a current of \(4 A\) is drawn from it. The internal resistance of the cell is :

The current density due to drift of electrons in a conductor is given by : (symbols have their usual meanings)

Pieces of copper and of silicon are initially at room temperature. Both are heated to temperature T. The conductivity of

For questions , two statements are given - one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :

Assertion (A) : When electrons drift in a conductor, it does not mean that all free electrons in the conductor are moving in the same direction.
Reason (R) : The drift velocity is superposed over large random velocities of electrons.

A current of \(0.8 A\) flows in a conductor of \(40 \Omega\) for 1 minute. The heat produced in the conductor will be

Assertion (A): When three electric bulbs of power \(200 \mathrm{~W}, 100 \mathrm{~W}\) and \(50 \mathrm{~W}\) are connected in series to a source, the power consumed by the \(50 \mathrm{~W}\) bulb is maximum.

Reason (R): In a series circuit, current is the same through each bulb, but the potential difference across each bulb is different.

Assertion (A) : The internal resistance of a cell is constant.
Reason (R) : Ionic concentration of the electrolyte remains same during use of a cell.

A cell of emf \(E\) is connected across an external resistance \(R\). When current ' \(I\) ' is drawn from the cell, the potential difference across the electrodes of the cell drops to \(V\). The internal resistance ' \(r\) ' of the cell is

The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is \( 0.25 \Omega \). What will be the effective resistance if they are connected in series?

Assertion (A) and Reason (R) type questions. Two statements are given — one labelled Assertion (A) and the other labelled Reason (R).
Select the correct answer from the codes (A), (B), (C) and (D)as given below.

Assertion (A) : The current density \((\vec{\mathrm{J}})\) at a point in a conducting wire is in the direction of electric field \((\vec{E})\) at that point.
Reason (R) : A conducting wire obeys Ohm's law.

10 resistors, each of resistance \(R\) are connected in series to a battery of emf \(E\) and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased \(n\) times. The value of \(n\) is :