K.C.S.E Physics Q & A - MODEL 2010PP2QN18

K.C.S.E Physics Q & A - MODEL 2010PP2QN18

​Figure 14a, is a diagram of a cathode ray tube. M and N are parallel vertical plates.

​(a) When switch S is open, a spot is seen at the centre of the screen as shown in figure 14(b).
(i) State what happens to the spot when S is closed. 
(ii) State what would happen to the spot if the potential difference across MN is increased. 
(iii) State what would be seen on the screen if the battery is replaced with an alternating emf of:
(I) a low frequency of about 1 Hz; 
(II) a high frequency of about 50Hz. 
(b) Explain the process by which electrons are produced at F. 
(c) State with a reason how the brightness of the spot can be increased. 
(d) The accelerating voltage of the tube is 1000V and the electron current in the beam is 1 .5mA. Determine the energy conveyed to the screen per second.

answers