In the figure the potentiometer wire of length $l =100\, cm$ and resistance $9\Omega$ is joined to a cell of emf $E_1 = 10V$ and internal resistance $r_1 = 1\Omega $. Another cell of emf $E_2 = 5\, V$ and internal resistance $r_2 = 2 \Omega $ is connected as shown. The galvanometer $G$ will show no deflection when the length $AC$ is ............... $cm$
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.*
When $5\ V$ potential difference is applied across a wire of length $0.1\ m$, the drift speed of electrons is $2.5 \times 10^{-4}$ $ms^{-1}$ . If the electron density in the wire is $8 \times 10^{28}$ $m^{-3}$ the resistivity of the material is close to
A potentiometer wire of length $300\,cm$ is connected in series with a resistance $780\,\Omega$ and a standard cell of emf $4\,V$. A constant current flows through potentiometer wire. The length of the null point for cell of emf $20\,mV$ is found to be $60\,cm$. The resistance of the potentiometer wire is$...\Omega$
The charge flowing through a resistance $R$ varies with time according to $Q = at -bt^2.$ The total heat produced in $R$ is : (assume that direction of current not reversed)
$A\,\,{5\,^o}C$ rise in the temperature is observed in a conductor by passing some current. When the current is doubled, then rise in temperature will be equal to ............. $^oC$
A wire of length $L$ and $3$ identical cells of negligible internal resistances are connected in series. Due to current, the temperature of the wire is raised by $\Delta T$ in a time $t$. A number $N$ of similar cells is now connected in series with a wire of the same material and cross-section but of length $2\, L$. The temperature of the wire is raised by the same amount $\Delta T$ in the same time $t$. the value of $N$ is
A $10\, m$ long wire of $20\,\Omega$ resistance is connected with a battery of $3\, volt$ $e.m.f.$ (negligible internal resistance) and a $10 \,\Omega$ resistance is joined to it is series. Potential gradient along wire in volt per meter is
A $220\, volt$ and $800\, watt$ electric kettle and three $220\, volt$ and $100\, watt$ bulbs are connected in parallel. On connecting this combination with $220\, volt$ electric supply, the total current will be ................ $ampere$