What do I have to do to calculate the value of the unknown resistor? The galvonometer reads 0 AMPS. I don't understand how the galvonometer changes according to where it's connected to the resistance wire. I thought amp meters read the same no matter where they're connected in the circuit. Just for clarification, in the middle wire, the part of wire before the galvonometer is 3ohms and the part of wire after the galvonometer is 7 ohms.