electro motive force (EMf) is the amount of force (voltage) needed to move unit chrage around the whole circuit is called emf.
all conduction conviction n radiation is a method to tranfer heat except tht.
conduction happens in solid, conviction in gasses and liquids, radiation in an emty place or vacum.
conduction needs medium, conviction needs medium (i.e gas inn liquids). radiation happens by ,eams of electromagnetic wave (i.e no need of medium, as it can travel throght vaccum shuch as heat from sun traveling throu space to reach earth..)
conduction happens without the movement of the whole body of a solid, conviction happens with the movement of liqiud or gasses, radiation just travels through...
hope this helped