Question

727 PM Sat May 11 ? 25% 3. For the simple CRT depicted below, describe how each suggested change in Va or Vd would affect the final deflection position of the electron beam. Effect on deflection, D Change in Voltage Vd is halved V, is tripled Vais increased by 1.5x and its polarity is reversed V, is quadrupled, Vd is doubled In a CRT, the deflection on the screen is 2.4 cm when the accelerating voltage is 480 V and the deflecting voltage is 36 V. What deflection will you see in the screen if the accelerating voltage is 960 V and the deflecting voltage is 18 V? 4.

Answer 1

CRT we can show that rightwardsdoublearrow D = v_deft times L times p/2S times V_acces (i) If all other things are kept constant, and only v_deft in halved. rightwardsdoublearrow D prime/D = (v_deft/2) times (Const.)/v_deft times const. rightwardsdoublearrow D prime = d/2 therefore deflection would be halved. \r\n (b) V_def = -V_def times 1s rightwardsdoublearrow D prime/D = -(v_def times 1.5) times const/v_def times const. rightwardsdoublearrow D prime = -1.5 D i.e deflection will be 1.5 times the original deflection. But this time the deflection will be in the other side of the centre point. (c) V_def prime = 2 v_def v_acc prime = 4 v_acc rightwardsdoublearrow D prime/D = (2 v_def times const)/4 v_acc/(v_def times const.)/v_acc = 2/4 = 1/2 D prime = 1/2 d rightwardsdoublearrow Deflection would be halved. \r\n D = 2.4 cm, v_acc = 480 V v_def = 36 V D prime = ?. V_acc = 960 V v_def = 18 V rightwardsdoublearrow D prime/D = const v_def prime /v_acc prime/const v_def/v_acc