Current Electri...

An ideal battery of emf $$2V$$ and a series resistance $$R$$ are connected in the primary circuit of a potentiometer of length $$1$$ m and resistance $$\Omega $$. The value of $$R$$ to give a potential difference of $$5$$ mV across the 10cm of potentiometer wire is:

The length of a potentiometer wire is $$l$$. A cell of emf $$E$$ is balanced at a length $$\dfrac{l}{5}$$ from the positive end of the wire. If the length of the wire is increased by $$\dfrac{l}{2}$$, the distance of the balance point with the same cell is

Resistance of a resistor at temperature $$t^{0}C$$ is $$R_{t}=R_{0}(1+\alpha t+\beta t^{2})$$. Here $$R_{0}$$ is the resistance at $$0^{0}C$$. The temperature coefficient of resistance at temperature $$t^{0}C$$ is

A potential difference of $$2 V$$ exists across a potentiometer wire of $$2 m$$ length. When the potential difference across a $$2\Omega $$ resistance of a second circuit is measured by the potentiometer wire, it amounts to $$5 mm$$ balancing length. The current in the second circuit is 

Two unknown resistrance X and Y are connected to left and right gaps of a meter bridge and the balancing point is obtained at 80 cm from left. When a 10$$\Omega $$ resistance is connected in paralle to x, the balance point is 50 cm from left. The values of X and Y respectively are

The resistance of a 240 V  , 200 W electric bulb when hot is 10 times the resistance when cold.The resistance at room temperature and the temperature coefficient of the filament are
(given working temperature of the filament is  2000$$^{0}$$C)

Aluminium$$\left ( \alpha =4\times 10^{-3}K^{-1} \right )$$  resistance of 60$$\Omega $$ and carbon $$\left ( \alpha =0.5\times 10^{-3}K^{-1} \right )$$ resistance 40$$\Omega $$ are connected in parallel. The combination is heated. The effective resistance is

Consider a thin square sheet of side $$L$$ and thickness $$t$$, made of a material of resistivity $$\rho $$. The resistance between two opposite faces, shown by the shaded areas in the figure is____

If a wire is stretched to make it $$0.1\%$$ longer, its resistance will 

Consider a long conductor, the middle of which is earthed. If the potential difference across the two ends of the conductor is $$220\ V$$, then what is the potential at the ends and the middle point?