"Current is measured by inserting a measuring device into the circuit to measure the flowing current. Voltage is typically measured in a circuit in parallel. Why isn't the current calculated from the voltage?"
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it doesnt work that way,
you can only read current by either putting a resistance inline and reading the voltage on both sides,
then calculate current from the loss,
or use a magnetic sensor to read the EM field radiating from the cable/ pcb track
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I dont quite understand question due to impedance in specific measurement, but I think that dmm actualy just do what you are write about, calculate current from voltage drop over the internal shunt resistor. DMM in current mode is just frontend interface to present you current on easy way.Why isn't the current calculated from the voltage?
My friend in early days are measuring current of mains socket... it was just a nice analog multimeter...
Last edited by harp; 02-29-2024, 03:09 PM.Comment
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Current is defined as the rate of electrons going through a point, so you have to get in between to know what's going on.
Technically if you know the voltage across two points and the resistance, you can compute current. The problem is that the resistance between the nodes tends to be unknown and may even change. Without it known and stable, there's no way to know current through two points (plus it may "leak" to another node).
Best you can do is using a clamp meter if you can't split the node.Comment
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