Oscilloscope

Someone might wondering how vertical amplifier in cathode ray oscilloscope can control sensitivity. What happen is that the electron beam is deflected as it drives the cathode ray oscilloscope's vertical depelection plates. The electron beam is deflected by some amount proportional to the voltage that is applied to those deflection plates. Then the input signal applied to the vertical amplifier gets amplified and causes the deflection to be proportional to the instantaneous input voltage. The amplifier is calibrated and has multiple gain settings so that the amount of input voltage required to cause a unit (normally 1 cm) deflection is controlled usually by a knob on the front panel.