An oscilloscope does not measure current directly: it measures voltage. To see a current waveform on screen, that current first has to be converted into a proportional voltage, using either a current probe or a shunt resistor. The short video below shows this in practice on a real bench setup.
Two ways to get from current to voltage
A «current probe» clamps around a conductor and uses a Hall effect or a current transformer to produce an output voltage proportional to the current flowing through it, without breaking the circuit. A «shunt resistor», by contrast, is inserted directly in series with the circuit, and the oscilloscope measures the small voltage drop across it, which is proportional to current through Ohm's law. Current probes are non intrusive and safer for high current or high voltage circuits, while shunts are simpler and often more accurate at low signal levels, at the cost of breaking into the circuit to insert them.
What to check before trusting the reading
The probe's bandwidth and maximum current rating both need to exceed what the circuit under test can actually produce, including any fast switching transients, not just the steady state current. A current probe rated well below the circuit's peak current, or below the frequency content of a fast switching edge, will quietly clip or roll off the very detail the measurement was meant to reveal.
ALLdata's role
ALLdata pairs its oscilloscope range with current probes matched to the current level and bandwidth a given application actually needs, from low power signal work to high current power electronics.
Not sure which current probe fits your measurement? Talk to an ALLdata engineer, or browse our oscilloscope range.