Descriptions of these probes follow, with more emphasis given to the passive probe since this is the probe type that allows you the most flexibility of use. Many modern oscilloscopes provide special automated features built into the input and mating probe connectors. The act of connecting the probe to the instrument notifies the oscilloscope about the probe's attenuation factor, which in turn scales the display so that the probe's attenuation is figured into the readout on the screen. Some probe interfaces also recognize the type of probe, that is, passive active, or current. Lastly, the interface may act as a DC power source for probes.
Active probes have their own amplifier and buffer circuitry that requires DC power.
Most passive probes have some attenuation factor, such as 10X, 100X, and so on. By convention, attenuation factors, such as for the 10X attenuator probe, have the X after the factor. In contrast, magnification factors like X10 have the X first. Circuit loading becomes more pronounced at higher frequencies, so be sure to use this type of probe when measuring signals above 5 kHz. The 10X attenuator probe improves the accuracy of your measurements, but it also reduces the amplitude of the signal seen on the screen by a factor of 10.