1.a set of n identical resistors each of resistance R ohm,when connected in series have effective resistance X ohm and when resistors are connected in parallel have effective resistance as Y ohm.Find the relation between R,X&Y.

2. a wire of resistance 10 ohm is bent in the form of a closed circle.what is the effecti ve resistance between 2 points at the ends of any diameter of the circle

3.Define electrical resistivity.how is it related 2 electrical conductivity of the factors length,area of cross-section,nature of material and temperature.which one can control the resistive value of a conductor.

1-

*n* number of resistances of R*,*

First connected in series i.e.

Then connected in parallel combination i.e.

2-

Resistance of the wire, R = 10 ohm

Both the resistance are in parallel.

So the equivalent resistance of the wire along the points AB is ,

3-

**Conductivity:**

Conductivity is the measure of the ability of a material to conduct electricity.It is the inverse of resistivity.

Its standard unit is mho /m

**Resistivity:**

Resistivity is the resistance of a unit length with unit area of cross section of the material of the conductor.

Unit: ohm-m

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