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$10\,Cells$, each of emf $'E'$ and internal resistance $'r'$, are connected in series to a variable external resistance. Figure shows the variation of terminal potential difference of their combination with the current drawn from the combination.$Emf$ of each cell is ............. $V$
A set of $n$ equal resistors, of value $R$ each, are connected in series to a battery of emf $E$ and internal resistance $R.$ The current drawn is $I.$ Now, the $n$ resistors are connected in parallel to the same battery. Then the current drawn from battery becomes $10\,I.$ The value of $n$ is
A potentiometer wire has length $4\,\, m$ and resistance $8\,\,\Omega $. The resistance that must be connected in series with the wire and an accumulator of e.m.f. $2\,\, V,$ so as to get a potential gradient $1\,\, m \,V$ per $cm$ on the wire is ............. $\Omega$
The resistance of a coil is $4.2\, \Omega$ at $100\,^o C$ and the temperature coefficient of resistance of its material is $ 0.004\,^o C$. Its resistance at $0\,^o C$ is ............. $\Omega$
A heating element has a resistance of $100\,\Omega $ at room temperature. When it is connected to a supply of $220\,V,$ a steady current of $2\,A$ passes in it and temperature is $500\,^oC$ more than room temperature. What is the temperature coefficient resistance of the heating element?
A wire of length $100\, cm$ is connected to a cell of emf $2\,V$ and negligible internal resistance. The resistance of the wire is $3\,\Omega $. The additional resistance required to produce a potential difference of $1\, mV/cm$ is ............. $\Omega$