Fundamental Electrical and Electronic Principles, Third Edition

224 Fundamental Electrical and Electronic PrinciplesV.C.V mH.C.I m (ref)6.15 The Cathode Ray OscilloscopeFig. 6.32Vm H.C.2V.C.2 21. 44210.4122so, Vm 23.83 Vtan1V.C.φ tan1104 . 12 tan10.4856H.C. 21.44and, φ 0.452 radHence, the phasor sum, v 23.83 sin (628 t 0.452) volt AnsThe name of this instrument is more often abbreviated to the oscilloscope,the ‘ scope, or CRO. It is a very versatile instrument, that may be used tomeasure both a.c. and d.c. voltages. For d.c. measurements, a voltmeteris usually more convenient to use. The principal advantages of theoscilloscope when used to measure a.c. quantities are:1 A visual indication of the waveform is produced.2 The frequency, period and phase angle of the waveform(s) can bedetermined.3 It can be used to measure very high frequency waveforms.4 Any waveshape can be displayed, and measured with equal accuracy.5 The input resistance (impedance) is of the same order as a digitalvoltmeter. It therefore applies minimal loading effect to a circuit towhich it is connected.6 Some oscilloscopes can display two or more waveformssimultaneously.Cathode Ray Tube The basic arrangement of a crt is shown inFig. 6.33 . The main components are contained within an evacuatedelectrongunanodesXdeflectionY deflectiongraphitecoatingFig. 6.33