I enjoy learning new things every time I do a problem set. Take the wheatstone bridge for example. Upon my initial observation, I concluded that the total upper electric potential(V1 + V2) minus the lower electric potential(V3 + V4) ought to give the electric potential that exists across the ammeter between the upper and lower sections of the wheatstone bridge(V5). HOWEVER, this is not NOT NOT!!!! TRUE. The electric potential that can exist across the ammeter, R5, is V1 - V3. or, V2 - V4. And, the battery EMF is only the sum of V1 and V2 or sum of V3 and V4. the potential across R5 DOES NOT affect the amount of EMF that is necessary from the battery. This implies that getting rid of the Ammeter and R5 connections will ONLY alter the currents across R1 and R2 or R3 and R4 without affecting the sum of V1 and V2 or V3 and V4 AND without altering the total current that comes out of the Battery.