The length of the wire is increased by 1 mm on the application of a given load. In a wire of the same material but of length and radius twice that of the first, on application of the same force, extension produced is

Q. A wire extends by 1 mm when a force is applied. What will be the elongation(in mm) in wire of same material if the force is doubled on the wire of same length and half the radius?

Q. A copper wire of length 1m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is

Join BYJU'S Learning Program

Which of the following wires of the same material will have higher resistance :-

The correct option is C radius is 1 mm and the length is 80 m.Resistance, R=ρlπr2For same material resistivity, ρ is constant.Thus, R∝l and R∝1r2So, minimum radius r and maximum length l will give the highest resistance.

The correct option is C radius is 1 mm and the length is 80 m.
Resistance, $R = \frac{ρ l}{π r^{2}}$
For same material resistivity, $ρ$ is constant.
Thus, $R \propto l$ and $R \propto \frac{1}{r^{2}}$
So, minimum radius r and maximum length l will give the highest resistance.