Ohm's Law

A wire of  $15\mathrm{\Omega }$ resistance is gradually stretched to double its original length. It is then cut into two equal parts. These parts are then connected in parallel across a $3.0 \mathrm{V}$ battery. Find the current drawn from the battery.

Derive an expression for the resistivity of a good conductor, in terms of the relaxation time of electrons.

Two metallic wires of the same material have the same length but cross-sectional area is in the ratio $1:2$. They are connected (i) in series and (ii) in parallel. Compare the drift velocities of electrons in the two wires in both the cases (i) and (ii).

The relation between current and drift velocity is

A wire of length $L$ and cross-sectional area $A$ has resistance $R$. It carries a current $I$ when a voltage $V$ is applied to its ends. The wire is melted and drawn to double its length. If the same voltage were to be applied across the wire then

The current in a copper wire is increased by increasing the potential difference between its ends. Which one of the following statements regarding the number of charge carriers per unit volume in the wire and ${\mathrm{v}}_{\mathrm{i}}$, the drift velocity of the charge carriers is correct?

If $S$ is specific charge of an electron, find the momentum of all the free electrons (due to their drift velocity) per unit length of a straight conductor of uniform cross-section carries a current $I$.

Calculate the value of average drift velocity through a copper wire having an area of cross-section${10}^{-6} {\mathrm{m}}^2$, carrying a current of $2 \mathrm{A}$, If the number of electrons per cubic meter is $8\times {10}^{28}$.

Assertion: If an electron and proton enter an electric field with equal energy, then path of electron is more curved than that of proton.
Reason: Electron has a tendency to form curve.

In the circuit shown below (on the left) the resistance and the emf source are both variable.

The graph of seven readings of the voltmeter and the ammeter $(V$ and $I$, respectively) for different settings of resistance and the emf, taken at equal intervals of time $\Delta t$, are shown below (on the right) by the dots connected by the curve $E F G H$. Consider the internal resistance of the battery to be negligible and the voltmeter an ammeter to be ideal devices. (Take, $R_0\equiv \frac{V_0}{I_0}$

Then, the plot of the resistance as a function of time corresponding to the curve $E F G H$ is given by

In the uniform electric field of $E=1\times {10}^4 \mathrm{N} {\mathrm{C}}^{-1}$, an electron is accelerated from rest. The acceleration of the electron is nearly (Charge of electron $q=1.6\times {10}^{-19} \mathrm{C}$)

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it 

A conductor wire having ${10}^{29}$ free electrons/$m^3$ carries a current of $20A.$ If the cross-section of the wire is $1 m{m}^2,$ then the drift velocity of electrons will be 

A cell of emf $E$ having an internal resistance $r$ is connected to an external resistance $R$. The potential difference $V$ across the resistance $R$ varies with $R$ as shown by the curve,

When potential difference across a given copper wire is increase, drift velocity of charge carriers

In the figure the potential difference across $6 \mathrm{ohm}$ resistor is $48 \mathrm{V}$. Then the potential difference between $A$ and $B$ is

Substances that have constant resistance over a wide range of voltages are