Question

What change is noticed in cathode ray tube when the anode voltage is increased ?

• A. Brightness of the screen increases.
  
• B. Kinetic energy of electrons reaching the screen increases.
• C. Kinetic energy of electrons reaching the screen decreases.
• D. Kinetic energy of electrons reaching the screen remains the same.
  

Answer 1

The correct option is B Kinetic energy of electrons reaching the screen increases.

Kinetic energy of the electrons reaching the screen $K=eV$

where $V$ is the anode voltage and $e$ is the electronic charge.

As the anode voltage is increased, the electrons get accelerated at faster rate which results in increase in the kinetic energy (or velocity) of the electrons.