When a current of $2\, A$ flows in a battery from negative to positive terminal, the potential difference across it is $12\, V$. If a current of $3\, A$ flows in the opposite direction potential difference across the terminals of the battery is $15\, V$, the $emf$ of the battery is ............... $\mathrm{V}$
A$12.6$
B$13.2$
C$13.5$
D$14$
Medium
Download our app for free and get started
B$13.2$
b $\mathrm{T} . \mathrm{P.D.}=\mathrm{E}-\mathrm{I} \mathrm{r} \Rightarrow 12=\mathrm{E}-2 \mathrm{r}$ ..........$(1)$
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
If voltage across a bulb rated $220$ $volt-$ $100$ $watt$ drops by $2.5\%$ of its rated value, the percentage of the rated value by which the power would decrease is ............... $\%$
To get maximum current through a resistance of $2.5\,\Omega $, one can use $m$ rows of cells, each row having $n$ cells. The internal resistance of each cell is $0.5\,\Omega $. What are the values of $n$ and $m$ if the total number of cells is $45$ ?
Two resistors of $6\,\Omega $ and $9\,\Omega $ are connected in series to a $120\, volt$ source. The power consumed by the $6\,\Omega $ resistor is ........... $W$
A current through a wire depends on time as $i =\alpha_{0} t +\beta t ^{2}$ where $\alpha_{0}=20 A / s$ and $\beta=8 As ^{-2} .$ Find the charge crossed through a section of the wire in $15 \,s$ (in $C$)
$10\, Cells$, 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 ................ $V$