EXPERIMENTO DE J. J. THOMSON

Discovery of the Thomson Atom

This section discusses the discovery of the Thomson atom and the initial experiments with cathode ray tubes.

The First Subatomic Particle - The Thomson Atom

• In the 19th century, advancements in techniques allowed for the study of gases inside glass tubes.

• By applying an electric current to a highly evacuated glass tube, scientists observed a changing luminosity known as cathode rays.

• These rays traveled easily through vacuum and were named cathode rays because they emanated from the cathode.

• The cathode ray tube was essentially the first fluorescent lamp produced.

Understanding Cathode Ray Tubes

This section explores further experiments with cathode ray tubes and their significance.

Observations and Experiments

• Scientists applied electric currents to glass tubes with higher vacuums to observe changes in luminosity.

• As the vacuum inside the tube increased, it was observed that cathode rays could travel more easily through vacuum.

• The rays traveled from the negative cathode to the positive anode.

• These observations led to questions about what caused this phenomenon and what these rays were composed of.

J.J. Thomson's Experiments

This section focuses on J.J. Thomson's experiments that would change our understanding of atoms.

Modifying Cathode Ray Tubes

• J.J. Thomson modified a cathode ray tube by introducing electrically charged plates at opposite ends.

• These plates allowed for measuring deviations in the path of cathode rays when an electric current was established.

• It was observed that when no electric field was present, the cathode rays propagated in a straight line from one end to another.

• However, when an electric field was applied, the cathode rays curved, and the curvature increased with a stronger electric field.

Discovering Electrons

This section reveals J.J. Thomson's discovery of electrons and their significance in atoms.

Characteristics of Cathode Rays

• The characteristics of cathode rays depended on the materials used.

• J.J. Thomson discovered that cathode rays were composed of particles called electrons.

• This discovery was groundbreaking as it revealed that atoms were not indivisible but consisted of smaller subatomic particles.

The transcript is in Portuguese, so the summary is also provided in Portuguese.