The document discusses the cathode ray oscilloscope (CRO) and how it can be used as a voltmeter and ammeter by connecting it across components or measuring voltage drops across resistors. It explains how to read measurements from a CRO, such as measuring time period by multiplying the distance between cycles by the time base setting. Finally, it notes that the CRO can be used to study AC waveforms, with mains electricity in Europe operating at 50 Hz and the relationship between peak and RMS voltages.