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.

A physical quantity, associated with electrical conductivity, has the SI unit ohm-meter. Identify this physical quantity.

In the circuit diagram shown below, $V_A$ and $V_B$ are the potentials at points $A$ and $B$ respectively. Then. $V_A-V_B$ is

The terminal potential difference across $A$ and $B$ in the circuit shown is

Ends of two wires $A$ and $B$ having resistivity ${\rho }_{\mathrm{A}}=3\times {10}^{-5} \mathrm{\Omega } \mathrm{m}$ and ${\rho }_{\mathrm{B}}=6\times {10}^{-5} \mathrm{\Omega } \mathrm{m}$ of same cross section area joined in series together to from a single wire. If the resistance of the joined wire does not change with temperature, then find the ratio of their lengths $\frac{l_A}{l_B}$, given that temperature coefficient of resistivity of wire $A$ and $B$ is ${\alpha }_{\mathrm{A}}=4\times {10}^{-5} °{\mathrm{C}}^{-1}$ and ${\alpha }_{\mathrm{B}}=-6\times {10}^{-6} {\mathrm{CC}}^{-1}$. Assume that mechanical dimensions do not change with temperature

A cylindrical conductor of length $l$ and inner radius $R_1$ and outer radius $R_2$ has specific resistance $\rho$. A cell of emf $\epsilon$ is connected across the two lateral faces of the conductor. Find the current from the cell. 

The relationship between the current density $\overrightarrow{j}$ and the electric field $\overrightarrow{E}$ is given by $\overrightarrow{j}=\sigma \overrightarrow{E}$ equivalently represents

A solid metallic cuboid of homogeneous material having geometrical dimension as shown in the figure will have a ratio of resistances for the sense of current along $x$, $y$ and $z$ directions respectively, equal to

Current is flowing with a current density $J=480 \mathrm{A} \mathrm{c}{\mathrm{m}}^{-2}$ in a copper wire. Assuming that each copper atom contributes one free electron and given that

Avogadro number $=6.0\times {10}^{23}\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}\mathrm{s}\mathrm{ }{\mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$

Density of copper $=9.0\mathrm{g}\mathrm{ }{\mathrm{c}\mathrm{m}}^{-3}$

Atomic weight of copper $=64\mathrm{g}\mathrm{ }{\mathrm{m}\mathrm{o}\mathrm{l}}^{-1}$

The drift velocity of electrons is

A current of $2 \mathrm{A}$ is established in a circuit containing an aluminium resistor of length $30 \mathrm{cm}$. If the area of cross-section of the resistor is $0.003 {\mathrm{cm}}^2$ at a point P.The current density at that point 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,

In the shown circuit, what is the potential difference across $A$ and $B$?

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

A steady current $I$ is set up in a wire whose cross-sectional area decreases in the direction of the flow of the current. Then, as we examine the narrowing region

As shown in the schematic below, a rod of uniform cross-sectional area $A$ and length $l$ is carrying a constant current $i$ through it and voltage across the rod is measured using an ideal voltmeter. The rod is stretched by the application of a force $F$.

Which of the following graphs would show the variation in the voltage across the rod as function of the strain $\epsilon$ when the strain is small. Neglect Joule heating.

Two metal slabs of equal lengths, equal cross sectional areas and having resistances in the ratio $1:2$ are connected first in series and then in parallel separately. The ratio of their effective conductivities is

A graph drawn between current $I$ and voltage $V$ in a conductor is as shown in the figure. The changes in the resistance in $1^{\text{st }}$ and $3^{\text{rd }}$ parts respectively

A cylindrical conductor has a uniform cross-section. The resistivity of its material increases linearly from left end to right end. If a constant current is flowing through it and at a section distance $x$ from left end, the magnitude of electric field intensity is $E$, which of the following graphs is correct?

In the given circuit ammeter and voltmeter are ideal and battery of $6 \mathrm{V}$ has internal resistance $1 \mathrm{\Omega }$. The reading of voltmeter and ammeter is