Shunt resistors are commonly used to measure current in power circuits, by producing a small voltage drop in direct proportion to the circuit current. They are especially useful for measuring complex current waveforms in AC circuits, since they do not distort the waveform at all.
Suppose you wished to measure the current waveform in this power circuit by using an oscilloscope to measure voltage dropped across the shunt resistor:
If you connect an oscilloscope to the power circuit as shown, very bad things will happen, like the oscilloscope's ground clip melting, with lots of sparks! Why this connection setup is incorrect and how to resolve this problem?