In an experiment to find $emf$ of a cell using potentiometer, the length of null point for a cell of emf $1.5\,V$ is found to be $60\,cm$. If this cell is replaced by another cell of $emf\; E$. the length-of null point increases by $40\,cm$. The value of $E$ is $\frac{x}{10} V$. The value of $x$ is $............$
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In the given potentiometer circuit arrangement, the balancing length ${AC}$ is measured to be $250$ ${cm}$. When the galvanometer connection is shifted from point $(1)$ to point $(2)$ in the given diagram, the balancing length becomes $400\, {cm}$. The ratio of the emf of two cells, $\frac{\varepsilon_{1}}{\varepsilon_{2}}$ is -
A cylindrical resistance is connected across battery $\varepsilon $ . Cylinder has uniform free electron density, mid part of cylinder has larger radius as shown in figure. Then $V_d$ (drift velocity) $V/S$ (distance across the length of the resistance)
A wire of resistance $12\,ohms$ per meter is bent to form a complete circle of radius $10\, cm.$ The resistance between its two diametrically opposite points, $A$ and $B$ as shown in the figure is
A platinum resistance thermometer has a resistance of $50\,\Omega $ at $20\,^o C$. When dipped in a liquid the resistance becomes $76.8\,\Omega $. The temperature coefficient of resistance for platinum is $\alpha = 3.92 \times {10^{ - 3}}\,^o C$. The temperature of the liquid is .............. $^o C$
An electric toaster has resistance of $60\ \Omega$ at room temperature $\left(27^{\circ} \mathrm{C}\right)$. The toaster is connected to a $220 \mathrm{~V}$ supply. If the current flowing through it reaches $2.75 \mathrm{~A}$, the temperature attained by toaster is around : (if $\alpha=2 \times 10^{-4} /{ }^{\circ} \mathrm{C}$ )