Current Electri...

A potentiometer wire 10 m long has a resistance of 40$$\Omega$$. It is connected in series with a resistance box and a 2V storage cell. If the potential gradient along the wire is 0.1 mV/cm ,  the resistance in the box is

In a potentiometer of ten wires, the balance point is obtained on the sixth wire. To shift the balance point to eighth wire, we should

A wire of resistance $$20\Omega $$ is bent in the form of a square. The resistance between the ends of diagonal is:

Assertion : The equivalent resistance between the points X and Y in the figure is 10.
Reason : According to Wheatstone bridge, points A and C have the same potential.

The resistance of a bulb filament is 100$$\Omega $$ at a temperature of 100$$^{0}$$C. If its temperature coefficient of resistance be 0.005 per $$^{0}$$C , its resistance will become 200$$\Omega $$ at a temperature of :

Three resistances each of $$3\Omega $$ are connected as shown in figure. The resultant resistance between A and F is:

The resistance of a wire at temperature $$30 ^{\circ}\ C$$ is found to be  $$10\ \Omega$$ . Now to increase the resistance by $$10\%,$$  the temperature of the wire must be $$($$ The temperature coefficient of resistance of the material  of the wire is $$0.002\; {^{\circ}C}^{-1}$$ and reference temperature is $$0 ^{\circ}\ C)$$.

While connecting $$6$$ cells in a battery in series, in a tape recorder, by mistake one cell is connected with reverse polarity. If the effective resistance of load is $$24$$ ohm and internal resistance of each cell is one ohm and emf $$1.5\ V$$, the current delivered by the battery is

A wire has a diameter of $$0.2  mm$$ and a length of $$50  cm$$. The specific resistance of it's material is $$40\times 10^{-6}$$$$ohm  cm$$. The current through it, when a potential difference of $$2  V$$ is applied across it, is

A carbon filament has resistance of 120$$\Omega $$ at $$0^{0}C$$. The resistance of a copper filament connected in series with carbon so that the combination has same resistance at all temperatures must be
$$\alpha $$ of carbon $$= -7\times 10^{-4}/^{0}C$$; $$\alpha $$ of copper $$=4\times 10^{-3}/^{0}C$$