What are the one main components of cathode ray tubes?
A) Electron gun
B) Cathode tube
C) U-tube
D) None of these

Hint: Use the concept of the cathode ray tube and working of it. Write the components of the cathode ray tube one by one and then match from the given option to find the correct answer. The main component of a cathode ray tube is an electron gun.

Complete step by step solution:
A type of vacuum tube with the function of producing an image on its display screen as a form of video signal is known as the cathode ray tube. It is possible if the electron beam from its electron guns strikes on the phosphorescent surface.

The functions of cathode ray tube are as follows:
Modulation of the electron beams.
Accelerate the electron beams at high velocity.
Deflection of the electron beam onto the phosphorous screen.

The components of a cathode ray tube are as follows.
Electron Gun.
Internal electrostatic deflection plates.
A fluorescent screen.

An evacuated glass envelope is used in the cathode ray tube that has some properties as shown below.
It should be large.
It should be deep.
It should be heavy.
It should be relatively fragile.
If the electrons are emitted from the electron gun and passing through the control grid then the potential will be highly positive.
The beam which strikes the fluorescent screen gives a bright spot which means converting the passing electrical signal into the visual pattern observed on screen.

Hence, from the above explanation it is concluded that the correct option is A.

Note: The other main component of cathode ray tube is deflection yoke and the main function of this is to control the direction of the electron beam. It also creates the electric and magnetic field.