Figure 3 shows the main features of a cathode ray tube (CRT) of a cathode ray oscilloscope (CRO).

(i) Describe how the electrons are produced in the tube.
(ii) State and explain the function of the grid.
(iii) State what would be observed on the screen if an a.c voltage is connected across the y-plates.
(iv) State how the deflection system of a television differs from that of a CRO.
(v) Give the reason why it is possible to have a wider screen in the television in the television set than on the CRO.

Answer:

i)- The heat from the filament heats up cathode causing the electrons to be dislodged from the
surface.

ii)- The grid controls the intensity of the electron beam reaching the screen hence brightness. It is negatively charged to repel the electrons hence increasing or decreasing the number reaching the screen.

iii)- A vertical line would appear.

iv)- Deflection in TV is by magnetic fields while the deflection in C.R.O is caused by
electric field

v)- Magnetic field produces wider deflection on electrons.

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