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 $............$
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The four arms of a Wheatstone bridge have resistances as shown in the figure. A galvanometer of $15\, \Omega$ resistance is connected across $BD$. Calculate the current through the galvanometer when a potential difference of $10\, V$ is maintained across $AC.$
If an electron revolves in the path of a circle of radius of $0.5 × 10^{-10}\, m$ at frequency of $5 × 10^{15}$ $cycles/s$ the electric current in the circle is ..................$mA$ (Charge of an electron $=1.6 × 10^{-19}\, C$ )
The internal resistance of a primary cell is $4\, ohm$. It generates a current of $0.2\, amp$ in an external resistance of $21\, ohm$. The rate at which chemical energy is consumed in providing the current is .............. $J/s$
A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2.0\,V$ and a negligible internal resistance. The potentiometer wire itself is $4\,m$ long. When the resistance $R,$ connected across the given cell, has values of $(i)$ infinity $(ii)$ $9.5\,\Omega$ the balancing lengths on the potentiometer wire are found to be $3\,m$ and $2.85\,m,$ respectively. The value of internal resistance of the cell is ............... $\Omega$
In a potentiometer (see figure) a balance is obtained at a length of $400\ mm$ when using a known battery of emf $1.6\ V$. After removing this battery, another battery of unknown emf is used and balance is obtained at a length of $650\ mm.$ The emf of unknown battery is ............. $volt$
Consider an electrical circuit containing a two way switch $^{\prime}{S}^{\prime}$. Initially ${S}$ is open and then ${T}_{1}$ is connected to ${T}_{2} .$ As the current in ${R}=6 \,\Omega$ attains a maximum value of steady state level, ${T}_{1}$ is disconnected from ${T}_{2}$ and immediately connected to ${T}_{3} .$ Potential drop across ${r}=3\, \Omega$ resistor immediately after $T_{1}$ is connected to $T_{3}$ is $....\,V.$ (Round off to the Nearest Integer)