Ohm's Law

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

Electric _____ between two points in an electric circuit carrying some current is defined as the work done to move a unit charge from one point to the other.

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

The length of a given cylindrical wire is increased by $100\%$. Due to the consequent decrease in diameter the change in the resistance of the wire will be

The specific resistance of a wire is $\rho ,$ its volume is $3 {\mathrm{m}}^3$ and its resistance is $3$ ohms, then its length will be:-

In the following diagram current in the $5\mathrm{\Omega }$ resistor is (when the internal resistance of the battery is zero) :-

A wire of resistance $4\mathrm{ }\mathrm{\Omega }$ is used to wind a coil of radius $7\mathrm{ }\mathrm{c}\mathrm{m}$. The wire has a diameter of $1.4\mathrm{ }\mathrm{m}\mathrm{m}$ and the specific resistance of its material is $2\times {10}^{-7}\mathrm{ }\mathrm{\Omega }\mathrm{ }\mathrm{m}$. The number of turns in the coil is

Find the radius of the wire of length $25 \mathrm{m}$ needed to prepare a coil of resistance $25 \mathrm{\Omega }$ ( Resistivity of material of wire is $3.142\times {10}^{-7} \mathrm{\Omega } \mathrm{m}$) 

The product of resistivity and conductivity of a conductor depends on -

A potential of $120 \mathrm{V}$ is applied across the ends of a cylindrical copper rod of length $1 \mathrm{cm}$ and radius $2.0 \mathrm{mm}$. Find the value of the current through the rod. (The resistivity of copper is $1.7\times {10}^{-8} \mathrm{\Omega m}$.)

The voltage current graph of conductor at two different temperature are shown in the Figure. If the resistances corresponding to these temperatures are $R_1$ and $R_2$ then which of the following statements is true.

A $6 \mathrm{V}$ battery is connected to the terminals of a $3 \mathrm{m}$ long wire of uniform thickness and resistance of $100 \mathrm{\Omega }.$ The difference of potential between two points on the wire separated by a distance of $50 \mathrm{cm}$ will be

Electrical resistivity of a given metallic wire depends upon

The area of cross section, length and density of a piece of metal of atomic weight $60$ are ${10}^{-6} m^2, 1 m,$ and $5\times {10}^3 kg{m}^{-3}$ respectively. If every atom contributes one free electron, then drift velocity is (charge of $e=1.6\times {10}^{-19} \mathrm{C}$.)

Find the potential difference (in $\mathrm{V}$) between points $A$ and $B$, shown in the circuit.

The masses of the three wires of copper are in the ratio of $1:3:5$ and their length are in the ratio of $5:3:1$. The ratio of their electrical resistance is,