A new flashlight cell of $e.m.f.$ $1.5\, volts$ gives a current of $15\, amps$, when connected directly to an ammeter of resistance $0.04\,\Omega $. The internal resistance of cell is ........... $\Omega$
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The capacitor $C$ is initially without charge.$X$ is now j oined to $Y$ for a long time, during which $H_1$ heat is produced in the resistance $R$. $X-Y$ connection is removed and $X$ is now joined to $Z$ for a long time, during which heat $H_2$ is produced in $R$.
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 current $i_1$ and $i_2$ through the resistors $R_1(=10\,\Omega )$ and ${R_2}\left( { = 30\,\Omega } \right)$ in the circuit diagram with $E_1 = 3\,V$, $E_2 = 3\,V$ and $E_3 = 2\,V$ are respectively
Two batteries, one of $emf$ $18\, volts$ and internal resistance $2\,\Omega $ and the other of $emf$ $12\, volt$ and internal resistance $1\,\Omega $, are connected as shown. The voltmeter $V$ will record a reading of .............. $\mathrm{volt}$
The resistance of a wire of iron is $10\, ohms$ and temp. coefficient of resistivity is $5 \times {10^{ - 3}}\,^oC$. At $20\,^oC$ it carries $30$ milliamperes of current. Keeping constant potential difference between its ends, the temperature of the wire is raised to $120\,^oC$. The current in milliamperes that flows in the wire is