simple chemical cell問題!!

if you only put silver or copper in a beaker of dilute sulphuric
acid, no reaction occurs.
but this time you connect a bulb across a silver electrode
and a copper electrode and use dilute sulphuric acid as
electrolyte. there is reaction. since copper is higher than silver
in metal reactivity series. copper will lose electron to form
copper ii ion . at the other side, hydrogen ion will gain
electron to form hydrogen. if the voltage is high , the bulb
may light up. difference in metal reactivity can make a
circuit like this , but if the voltage is not high , the bulb will
not light up.