When an electric current is passed through acidified water the hydrogen and oxygen are formed what type of effect of current is illustrated by this statement?

This is electrolysis reaction in water. This is one experimental method of showing water is a compound composed of the elements hydrogen and oxygen atoms i.e. by splitting liquid water into two gaseous element molecules of hydrogen (H2) and oxygen (O2).

Water only ionises to a tiny extent giving minute concentrations of hydrogen ions and hydroxide ions, so the presence of high concentrations of hydrogen ions (H+ or H3O+) andsulfate ions (SO42–) from the acid, makes water a much better electrical conductor (a much better electrolyte solution). These small extra ion concentrations of hydrogen ions (H+) and hydroxide ions (OH–) are from the self-ionisation of water itself