I found the choices:
A. The beam was attracted to a positive charge and repelled by a negative charge, showing that atoms contain small, negatively charged particles.
B. The beam was attracted to a negative charge and repelled by a positive charge, showing that atoms contain small, positively charged particles.
C. The beam was positively charged and had significant mass, showing that atoms have a positive, dense nucleus.
D. The beam was neutral and had significant mass, showing that atoms contain neutral particles in the nucleus.
Answer:
A. The beam was attracted to a positive charge and repelled by a negative charge, showing that atoms contain small, negatively charged particles.
Explanation:
J.J Thomson in 1897 carried out experiments on the gas discharge tube which led to the discovery of cathode rays also known as electrons. He observed the following properties:
- the rays move in a straight line and they cast a shadow of an object along their path.
- they cause mechanical paddles to rotate because they posses kinetic energy.
- they attract positive charges and repel negative charges.
The last property led the plum pudding model of the atom. In this model Thomson suggested an atom as pool of electron surrounded by positive charges based on the fact that cathode rays attracts positive charges.
