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$10$ resistors, each of resistance $R$ are connected in series to a battery of $emf$ $E$ and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased $n$ times. The value of $n$ is :
The current in a wire varies with time according to relation $I = 4 + 2t$. The quantity of charge which has passed through a crosssectionn of the wire during the time $t = 2\, s$ to $t = 6\, s$ will be .............. $\mathrm{C}$
Two cells, having the same $e.m.f.$ are connected in series through an external resistance $R.$ Cells have internal resistances $r_1$ and $r_2\,\, (r_1 > r_2)$ respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of $R$ is
Electric bulb $50\, W$ - $100\, V$ glowing at full power are to be used in parallel with battery $120\, V$, $10 \,\Omega$. Maximum number of bulbs that can be connected so that they glow in full power is
In Wheatstone's bridge $P = 9\, ohm$, $Q = 11\, ohm$, $R = 4\,ohm$ and $S = 6\,ohm$. How much resistance must be put in parallel to the resistance $S$ to balance the bridge ............... $ohm$
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 $............$
A uniform heating wire of resistance $36\, \Omega$ is connected across a potential difference of $240\, {V}$ The wire is then cut into half and potential difference of $240\, {V}$ is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be $1: {x}$, where ${x}$ is........... .
The drift velocity of electrons for a conductor connected in an electrical circuit is $V _{ d }$. The conductor in now replaced by another conductor with same material and same length but double the area of cross section. The applied voltage remains same. The new drift velocity of electrons will be