ACTIVITY 1
Go through the following explanation on the production and characteristics of cathode rays and answer the questions at the Evaluation section.
Production of cathode rays
They are produced by a set up called a discharge tube where a high voltage source usually referred to as extra high tension (EHT), supply connected across a tube containing air at low pressure thereby producing a luminous electron discharge between the two brass rods placed at opposite ends of the tube. These electron discharges are called cathode rays which were discovered by J.J Thomson in the 18th century.
Properties of cathode rays
- They travel in straight lines
- They are particulate in nature i.e. negatively charged electrons
- They are affected by both magnetic and electric fields since they are deflected towards the positive plates
- They produce fluorescence in some materials
- Depending on the energy of the cathode rays they can penetrate thin sheets of paper, metal foils
- When cathode rays are stopped they produce X-rays.
- They affect photographic plates.
ACTIVITY 2
Watch the video clip below on production & characteristics of cathode rays and answer the questions at the Evaluation section.