What controls the number of electrons that reach the fluorescent screen in a cathode ray tube A anode B cathod Cdeflecting plate D grid?

I am about to take this exam myself, so maybe I can help both of us with this.

The choices are:

A.) anode

B.) cathode

C.) deflecting plates

D.) grid

The answer starts on page 86 of your study guide, titled "Cathode Ray Tubes".

In this illustration, current supplied to the heater causes emission of electrons from the cathode. Those electrons pass toward the anodes through an opening in the control grid. The grid limits the number of electrons that can pass through it, and the anodes cause the electrons passing the grid to a point on the fluorescent screen. Also, two deflecting plates are placed in the path of the beam electrons. When a voltage is applied to these plates, the beam is deflected toward the positively charged plates. If the applied voltage is alternating, the beam moves up and down through its normal central position, and the luminous spot moves on the screen in the same way.

Based on this information I have deduced thus...

The answer is not A.) anode. Because the anodes job is to pass the electrons the grid allowed through to the point on the fluorescent screen.

The answer is not B.) cathode. Because the cathode when heated causes emission of electrons, its purpose is not to limit the number of electrons, just to produce the electrons. The answer is not C.) deflecting plates. Because their job is to use the emitted electrons allowed through the grid to make the projection. So, the answer must be D.) Grid. Because the grid limits the number of electrons that can pass through it!

Like I said, I have not taken this exam myself. However, based on the reading material, D just makes sense!