To find the resistance of a galvanometer by the half deflection method the following circuit is used with resistances $R_1 = 9970\,\Omega,$ $R_2 = 30\,\Omega$ and $R_3 = 0\,\Omega.$ The deflection in the galvanometer is $d$. With $R_3 = 107\,\Omega$ the deflection changed to $\frac {d}{2}$The galvanometer resistance is approximately ............... $\Omega$
JEE MAIN 2013, Diffcult
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One $kg$ of water, at $20\,^oC$, is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of $20\, \Omega $. The rms voltage in the mains is $200\, V$. Ignoring heat loss from the kettle, time taken for water to evaporate fully, is close to.......... $\min$ [Specific heat of water $= 4200\, J/kg\, ^oC$), Latent heat of water $= 2260\, k\,J/kg$]
Two wires '$A$' and '$B$' of the same material have their lengths in the ratio $1 : 2$ and radii in the ratio $2 : 1$. The two wires are connected in parallel across a battery. The ratio of the heat produced in '$A$' to the heat produced in '$B$' for the same time is
$A$ battery of $\mathrm{emf}$ $E$ and internal resistance $r$ is connected across a resistance $R$. Resistance $R$ can be adjusted to any value greater than or equal to zero. Agraph is plotted between the current $(i)$ passing through the resistance and potential difference $(V) $ across it. Select the correct alternative $(s)$.
We have a galvanometer of resistance $25\,\Omega $. It is shunted by a $2.5\,\Omega $ wire. The part of total current that flows through the galvanometer is given as
In the circuit shown, the power developed in the $6\,\Omega $ resistor is $6\,W.$ The power developed in the $4\,\Omega $ resistor is .............. $W$
You are given several identical resistances each of value $R = 10\,\Omega $ and each capable of carrying maximum current of $1\, ampere$. It is required to make a suitable combination of these resistances to produce a resistance of $5\,\Omega $ which can carry a current of $4\, amperes$. The minimum number of resistances of the type $R$ that will be required for this job