An experiment is set up to investigate the magnetic properties of different metals. A student places an unmagnetised metal rod on a digital electronic balance.
A strong permanent bar magnet is held vertically and stationary just above the rod, with its North pole (NNN) facing the top of the rod, as shown below.
The experiment is carried out first using an unmagnetised nickel rod, and then repeated using an unmagnetised copper rod of identical dimensions and mass.
Which row correctly describes what happens to the reading on the electronic balance in each case when the magnet is brought close?
Nickel rod: reading increases; Copper rod: reading remains unchanged.
Nickel rod: reading decreases; Copper rod: reading remains unchanged.
Nickel rod: reading decreases; Copper rod: reading decreases.
Nickel rod: reading remains unchanged; Copper rod: reading remains unchanged.