A cell of $emf$ $E$ and internal resistance $r$ is connected in series with an external resistacne $nr.$ Then, the ratio of the terminal potential difference to $emf$ is
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A current of $5\; {A}$ is passing through a non-linear magnesium wire of cross-section $0.04\; {m}^{2}$. At every point the direction of current density is at an angle of $60^{\circ}$ with the unit vector of area of cross-section. The magnitude of electric field at every point of the conductor is ....${V} / {m}$ (Resistivity of magnesium is $\rho=44 \times 10^{-8}\, \Omega m$)
An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of $4/3$ and $2/3$, then the ratio of the currents passing through the wire will be
A uniform metallic wire carries a current $2\,A$. when $3.4\,V$ battery is connected across it. The mass of uniform metallic wire is $8.92 \times 10^{-3} \,kg$. density is $8.92 \times 10^3\,kg / m ^3$ and resistivity is $1.7 \times 10^{-8} \Omega- m$. The length of wire is $l=............\,m$
In a meter bridge experiment, resistances are connected as shown in the following figure. The balancing length $l_1$ is $55\, cm$. Now, an unknown resistance $x$ is connected in series with $P$ and the new balancing length is found to be $75\, cm$. The value of $x$ is
In a potentiometer experiment shown here, for the position $X$ of the jockey $J,$ there occurs a null deflection in the galvanometer. Then the potential difference between points $A$ and $X$ is ................ $V$
A cube is formed with ten identical resistances $R$ (thick lines) and two shorting wires (dotted lines) along the arms $A C$ and $B D$ as shown in the figure below. Resistance between point $A$ and $B$ is ...........$\Omega$