A metal wire 1.50 m long has a circular cross section of radius 0.32 mm and an end-to-end resistance of 90.0 Ohms. The metal wire is then stretched uniformly so that its cross-section is still circular but its total length is now 6.75 m. What is the resistance of the wire after stretching? (Units: Ohm.)

So after stretching new resistance will be 0.1823 ohm

Explanation:

We have given initially length of the wire

Radius of the wire

Resistance of the wire initially

We know that resistance is equal to ,here is resistivity, l is length and A is area

From the relation we can say that

Now length of wire become 6.75 m

Volume will be constant

So

So

So