An iron wire and a copper wire of the same length have the same potential difference applied to them. What must be the ratio of their radii if the currents in the two wires are to be the same? (Ratio of the radius of iron wire to that of copper wire). For the resistivities of iron and copper use: rhoiron = 1.0 times 10-7 capital omega m; rhocopper = 1.7 times 10-8 capital omega m;

The ratio of their radii (Ratio of the radius of iron wire to that of copper wire) is 2.43

Explanation: Please see the attachments below

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

answerdmitry mendeleyev made a workable classification of the elements