Current Electricity

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of 2$$\Omega$$. The value of internal resistance of each cell is

Two cells of same emf but different internal resistances r₁ and r₂ are connected in series with a resistance R. The value of resistance R, for which the potential difference across second cell is zero, is :

Two sources of equal emfs are connected in series. This combination is connected to an external resistance R. The internal resistances of the two sources are $$r_{1}$$ and $$r_{2}$$ $$\left(r_{1}>r_{2}\right)$$. If the potential difference across the source of internal resistance $$r_{1}$$ is zero, then the value of R will be :

A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold, then, an electric current will

An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is :

Given below are two statements : Statement I : A uniform wire of resistance $$80 \,\Omega$$ is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be $$5 \,\Omega$$. Statement II: Two resistances 2R and 3R are connected in parallel in a electric circuit. The value of thermal energy developed in 3R and 2R will be in the ratio $$3: 2$$. In the light of the above statements, choose the most appropriate answer from the option given below

The $\mathrm{H}$ amount of thermal energy is developed by a resistor in $10 \mathrm{~s}$ when a current of $4 \mathrm{~A}$ is passed through it. If the current is increased to $16 \mathrm{~A}$, the thermal energy developed by the resistor in $10 \mathrm{~s}$ will be :

The Kirchhoff's first law $$\left( {\sum i = 0} \right)$$ and second law $$\left( {\sum iR = \sum E} \right),$$ where the symbols have their usual meanings, are respectively based on

The mass of product liberated on anode in an electrochemical cell depends on (where $$t$$ is the time period for which the current is passed).

The nagative $$Zn$$ pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by $$0.13g$$ in $$30$$ minutes. If the electrochemical equivalent of $$Zn$$ and $$Cu$$ are $$32.5$$ and $$31.5$$ respectively, the increase in the mass of the positive $$Cu$$ pole in this time is

A 200 $$\Omega$$ resistor has a certain color code. If one replaces the red color by green in the code, the new resistance will be :

The resistance of the series combination of two resistances is $$S.$$ When they are jointed in parallel the total resistance is $$P.$$ If $$S = nP$$ then the Minimum possible value of $$n$$ is

A uniform metallic wire has a resistance of 18 $$\Omega$$ and is bent into an equilateral triangle. Then, the resistance between any two vertices of the triangle is -

What equal length of an iron wire and a copper-nickel alloy wire, each of 2 mm diameter connected parallel to give an equivalent resistance of 3$$\Omega$$ ? (Given resistivities of iron and copper-nickel alloy wire are 12 $$\mu$$$$\Omega$$ and 51 $$\mu$$$$\Omega$$ cm respectively)

Five identical cells each of internal resistance 1$$\Omega$$ and emf 5V are connected in series and in parallel with an external resistance 'R'. For what value of 'R', current in series and parallel combination will remain the same?

Two resistors R₁ = (4 $$\pm$$ 0.8) $$\Omega$$ and R₂ = (4 $$\pm$$ 0.4) $$\Omega$$ are connected in parallel. The equivalent resistance of their parallel combination will be :

What will be the most suitable combination of three resistors A = 2$$\Omega$$, B = 4$$\Omega$$, C = 6$$\Omega$$ so that $$\left( {{{22} \over 3}} \right)$$$$\Omega$$ is equivalent resistance of combination?

An electric cable of copper has just one wire of radius 9 mm. Its resistance is 14 $$\Omega$$. If this single copper wire of the cable is replaced by seven identical well insulated copper wires each of radius 3 mm connected in parallel, then the new resistance of the combination will be :

Equivalent resistance between the adjacent corners of a regular n-sided polygon of uniform wire of resistance R would be :