Sampled AC Voltage measurement

1. How is AC and DC measured in CRO?
2. What is sampling rate of a signal?

How is AC and DC measured in CRO?

Measurement of AC/DC Current

First pass the unknown AC/DC current through a known value of resistor, say 10Ω. Then connect the voltage drop across it to y-input of CRO. If the unknown current is AC we will get a waveform, but if it is DC, we will get a straight line.

What is sampling rate of a signal?

Sampling rate or sampling frequency defines the number of samples per second (or per other unit) taken from a continuous signal to make a discrete or digital signal.