AIM: 1. Use of cathode ray oscilloscope (CRO) for voltage (AC AND DC) and frequency measurement (direct method) 2. To determine the frequency of unknown source using Lissajous pattern. Cathode Ray Oscilloscope (CRO) Cathode Ray Oscilloscope (CRO) is a versatile measuring instrument. The electrical parameters associated with ac signals such as voltage, current, frequency, phase etc. can be most conveniently measured using CRO. It not only measures these parameters but also displays the nature of the applied signal. (Analogue and digital meters are incapable of displaying the nature of the applied signal. Moreover , these meters do not measure peak value but they measure RMS values). Apart from the use of CRO for direct measurements of an electrical signal, it can also be used for measuring different physical quantities such as temperature, pressure, light intensity etc. with the help of transduce