What was Eugen Goldstein’s hypothesis?
Dalton’s atomic theory suggested that atoms are the smallest indivisible particles of matter. But in the year 1886, a German physicist, Eugen Goldstein conducted experiments and came up with a hypothesis, that proved that atoms can be further subdivided into smaller particles.
Canal Ray Experiment :
Apparatus
In this experiment, Goldstein used a discharge tube to observe a new kind of radiation. A discharge tube is a glass tube connected to two electrodes – a positively charged anode and a negatively charged cathode.
The cathode in this experiment was a perforated metal disc placed at the centre of the discharge tube. The anode was placed at one end of the discharge tube, and both the electrodes were connected to a battery through an external circuit.
Discharge tube
Procedure and observations
Extremely high electric potential was applied across the two electrodes. This led to the emission of rays from the negatively charged cathode to the positively charged anode because of opposite polarities. These rays were called the Cathode rays and consisted of negatively charged electrons.
Along with this, it was also observed that there were rays emitted from the anode. These rays moved towards the perforated cathode, passed through the holes and created a glow in the empty space behind.
From the above experiment, it was observed that the rays emitted from the anode were attracted towards the negatively charged cathode. This implied that the rays had a positive charge.
Goldstein named them Canal rays because of their movement through canal-like holes. They are also known as Anode rays or Positive rays.