An oscilloscope display grid or scale is called a

Physics Laboratory Manual n Loyd L ABOR AT ORY 38 Oscilloscope Measurements OBJECTIVES o Investigate the fundamental principles and practical operation of the oscilloscope using signals from a function generator. o Measure sine and other waveform signals of varying voltage and frequency. o Compare voltage measurements with the oscilloscope to voltage measurements using an alternating current voltmeter. EQUIPMENT LIST . Oscilloscope (typical direct current to 20 Mhz), alternating current voltmeter (high frequency capability) . Function generator (sine wave plus additional wave form such as a square wave or triangular wave), appropriate connecting wires (BNC to banana plug) COPYRIGHT ª 2008 Thomson Brooks/Cole THEORY The fundamental working part of an oscilloscope is a device called a cathode-ray tube (CRT). Its components include a heated filament to emit a beam of electrons, a series of electrodes to accelerate, focus, and control the intensity of the emitted electrons, two pairs of deflection plates that deflect the electron beam when there is a voltage between the plates (one pair for deflection in the horizontal direction and one pair for deflection in the vertical direction), and a fluorescent screen that emits a visible spot of light at the point where the beam of electrons strikes the screen. Together the heated filament and series of electrodes are called an electron gun. The electron gun and deflecting plates are arranged linearly inside an evacuated glass tube, and the fluorescent screen coats the glass tube at the opposite end of the tube from the electron gun as shown in Figure 38-1