A cathode-ray oscilloscope makes use of the process known as thermionic emission. Describe what happens during this process. In the space below, draw a labelled diagram of a cathode-ray oscilloscope. Include in your diagram the tube, the cathode, the accelerating anode, the focusing anode and both X- and Y-plates. Do not attempt to show any external circuits. A cathode ray is a beam of electrons. Suggest one way of controlling the number of electrons in the beam. One cathode-ray tube has 5000 V between the accelerating anode and the cathode. The beam of electrons carries a total charge of 0.0095 C in 5.0 s. Calculate the current caused by the beam, current = the energy transferred by the beam in 20 s. energy = . 0625_s11_qp_31 THEORY 2011 Paper 3, Variant 1 View