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.

Two conducting wires X and Y of same diameter but different materials are joined in series across a battery. If the number density of electrons in X is twice that in Y, find the ratio of drift velocity of electrons in the two wires would be:

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. 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 conductor.
D. The drift velocity of electron is inversely proportional to the length of the conductor.
E. The drift velocity increases with the increase in the temperature of conductor.

Choose the correct answer from the options given below:

In the electrical network shown in the figure, the potential difference across $3 \mathrm{\Omega }$ resistance will be

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?

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 

Two cylindrical rods of uniform cross-sectional area $A$ and $2A$, having free electrons per unit volume $2n$ and $n$ respectively are joined in series. A constant current $I$ flows through them in steady state. The ratio of the drift velocity of free electrons in the left rod to that of the right rod is $\left(\frac{V_{\mathrm{L}}}{V_{\mathrm{R}}}\right)$ is:
 

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

The resultant flow of current in a conductor in the absence of electric field is