Which scientist is credited with the discovery of the electron?

• A. Robert Millikan
• B. Ernest Rutherford
• C. Niels Bohr
• D. J.J. Thomson

Answer: (D)

Verified step by step guidance

1. Understand that the question is about identifying the scientist who discovered the electron, a fundamental subatomic particle.
2. Recall that the discovery of the electron involved experiments with cathode rays, which are streams of electrons observed in vacuum tubes.
3. Recognize that J.J. Thomson conducted experiments in 1897 using cathode ray tubes and measured the charge-to-mass ratio of the electron, leading to the identification of the electron as a particle.
4. Note that Robert Millikan is known for the oil drop experiment, which measured the charge of the electron, but did not discover it.
5. Remember that Ernest Rutherford is credited with discovering the nucleus, and Niels Bohr developed the Bohr model of the atom, but neither discovered the electron.