Current Electri...

How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of $$0.05$$ mV cm$$^{-1}$$?

A $$6V$$ battery of negligible internal resistance is connected across a uniform wire of length $$1 m$$. The positive terminal of another battery of e.m.f. $$4V$$ and internal resistance $$1\Omega$$ is joined to the point $$A$$ as shown in the figure. The ammeter shows zero deflection when the jockey touches the wire at the point $$C$$.

In the figure, the potentiometer wire $$AB$$ of length $$L$$ and resistance $$9r$$ is joined to the cell $$D$$ of emf $$\varepsilon$$ and internal resistance $$r$$. The cell $$C's$$ emf is $$\varepsilon/2$$ and its internal resistance is $$2r$$. The galvanomater $$G$$ will show no deflection when the length $$AJ$$ is

A brass disc and a carbon disc of same radius are assembled alternatively to make a cylindrical conductor. The resistance of the cylinder is independent of the temperature. The ratio of thickness of the brass disc to that of the carbon disc is $$\underline{\hspace{0.5in}}$$ .$$\alpha$$ is temperature coefficient of resistance & Neglect linear expansion

Calculate the value of current $$I_2$$ in the section of networks shown in figure.

Calculate the value of current $$I_4$$  in the section of networks shown in figure.

A wire of length $$L$$ and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised at $$\triangle T$$ in time $$t$$. $$N$$ number of similar cells is now connected in series with a wire of the same material and cross-section but of length $$2L$$. The temperature of the wire is raised by the same amount $$\triangle T$$ in the same time $$t$$. The value of $$N$$ is:

In a balanced wheat stone bridge, current in the galvanometer is zero. It remains zero when
$$[1]$$. battery emf is increased
$$[2]$$. all resistances are increased by 10 ohms
$$[3]$$. all resistances are made five times
$$[4]$$. the battery and the galvanometer are interchanged

Calculate the value of current $$I_3$$  in the section of networks shown in figure.

To measure a small resistance $$\sim 10^{-5}\Omega$$, one should used