Why are we so sure that there are only two types of electrical charge?
Because we have look far and wide, and only found two. (or three if you count neutral :) )
How far and how wide?
Is it possible to have multiple types of charge only two types of interaction between them?
Actually we called off the search on October 3, 1947. Budget ran out and they instead decided to pass it over to the search for the 16th way that you can make an Upside-down Pineapple Cake.
If there were multiple types of charge and they only interacted in two ways, then what would differentiate the types of charges? Electrodynamics is a theory that explains the behavior of the electromagnetic force. If you add redundant elements to this theory, how would you change anything?
There are also quark charges, ±1e/3 and ±2e/3, but quarks are very short-lived.
im having this doubt.. why is that 'total' charge is conserved...why dont we have all negative and all positive charge conserved...ie say total negative charges pre and post a reaction should be the same rt ?
Separately conserving positive charge (protons) and negative charge (electrons) is not observed in nature. Consider for example, the radioactive isotope copper-64 (an odd-odd nucleus with 29 protons). Sometimes it decays by beta- (electron) decay to a zinc isotope (30 protons), sometimes by beta+ (positron) decay to a nickel isotope (28 protons), and sometimes by capturing an atomic electron (in the K-shell) to become a nickel isotope. So sometimes the number of positive charges increases, and sometimes decreases. The number of negative charges (electrons) changes accordingly. The only observed conserved quantities are baryon numbers (neutrons + protons), lepton numbers (charged leptons + neutrinos), and total charge. This is even true when antiparticles (like antiprotons) are involved.
An electron and positron can both vanish together. Or, a pair can be created. Clearly, both kinds of charges' counts change. But they always change together.
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