In rings siagram ,the volatge provide in a circuit is same . But each appliance have a specefic voltage needed with which it works.whenthe circuit provides this volatge to the appliance ,this appliance works
Its not like in rings system,voltage is differenn but every appliance require diiferent voltage for their work
For example
if a bulb and tv is in a circuit,then cicuit provide equal current to both ,but since bulb require less voltage ,it take leass volatage from given and tv little more from the given