Originally Posted by StuM
Shunt? Hall effect DC clamp meter?
So to dispute the claim that to measure current you need to /be/ the path, you brought up shunts as a counterexample? And how exactly do /you/ think a shunt works?
You're getting close to a counterexample with Hall Effect, but you surround the wire you are measuring, and become coupled to it. So its not a great counterexample.
The OP seemed to be expecting a multimeter to be 'internally designed' to be able to measure current despite being hooked in parallel to the circuit they care about. The point of my post was that wouldn't be possible unless it had psychic powers. To measure current in a particular circuit, you need to be being influenced by that particular circuit. Really its not even a question of electronics
, its like information theory or something.