Tag: effect of electric current

Sea water contains more dissolved salts than the drinking water. 

A compass is an extremely simple device. A magnetic compass consists of a small, lightweight magnet balanced on a nearly frictionless pivot point. No matter where you stand on Earth, you can hold a compass in your hand and it will point toward the north and south pole.

This is because some of the electric energy is converted into heat energy, i.e., heating effect of electric current.

When a metal plate is getting heated, it may be due to the passage of direct current, alternating current or even induced current through the plate. As time varying magnetic field produces induced current  in the plate, so both (a) and (b) are correct.

A conductor has its own resistance. Due to the flowing current, certain heat is produced in the conductor according to the Joule's heating effect  i.e   $H = I^2Rt$.

Answer is A.

A metallic conductor has a large number of free electrons in it. When a potential difference is applied across the ends of a metallic wire, the free electrons begin to drift from the low potential to the high potential region. These electrons collide with the positive ions (the atoms which have lost their electrons). In these collisions, energy of the electrons is transferred to the positive ions and they begin to vibrate more violently. As a result, heat is produced. Greater the number of electrons flowing per second, greater will be the rate of collisions and hence more heat is produced.
Hence, the temperature of a metal wire rises when an electric current is passed through it because collision of conduction electrons with the atoms of metal gives them energy which appears as heat.

As we know,

Amount of heat produced in wire = $I^2R$

$Power=i^2R$