The electron was discovered by J. J. Thomson (Joseph John Thomson) in 1897 through his experiments with cathode rays. His work proved that atoms are not indivisible and contain smaller negatively charged particles called electrons.
J. J. Thomson, a British physicist at the Cavendish Laboratory (University of Cambridge), conducted experiments using a cathode ray tube. When he passed electricity through a vacuum tube, he observed a beam (cathode rays) that was deflected by electric and magnetic fields. This deflection showed that the rays were made of tiny negatively charged particles.
From these observations, Thomson concluded that these particles were much smaller than atoms and existed inside them. He initially called them “corpuscles,” but later they were renamed electrons, a term already suggested by Irish scientist George Johnstone Stoney.
This discovery was extremely important in the history of physics because it was the first evidence that atoms have internal structure. Before Thomson’s work, atoms were believed to be the smallest and indivisible units of matter.
Thomson’s discovery also led to the development of the “plum pudding model” of the atom, where electrons were imagined as embedded within a positively charged sphere.
In conclusion, the electron was discovered by J. J. Thomson in 1897, marking a major breakthrough in atomic physics and changing our understanding of matter forever.
Answered By Tara Verma
History of Physics & Scientific Discoveries ResearcherTara Verma is a practising teacher and education content writer with over 10 years of classroom experience across primary and secondary levels. She holds a Master's degree in Education (M.Ed.) from Delhi University and a Bachelor of Education (B.Ed.) from Jamia Millia Islamia — qualifications that ground her writing in both pedagogical theory and the day-to-day realities of teaching in India. Her content covers exam preparation strategies, learning methodologies, curriculum guidance, student mental health, career counselling for students, and the evolving state of school and higher education in India. Her work has appeared on platforms including TeacherVision India, Jagran Josh, and Careers360, where she writes for students, parents, and fellow educators who need content built on actual teaching experience — not theory alone. Over a decade of working directly with students across age groups and learning levels has given Tara a practical understanding of how education content should be written — clearly, accessibly, and with genuine awareness of the challenges students and teachers face on the ground. She has taught 1,000+ students, contributed to school curriculum development initiatives, and published 250+ articles on education across digital platforms. She is an active member of the National Council of Teachers of English (NCTE) India. Across all her writing, every recommendation is classroom-tested, every insight comes from direct teaching experience, and every article is held to the same standard she applies in her own classroom — accuracy, clarity, and genuine usefulness for the reader.
