Discovering the fundamental particle that powers our universe. Dive into the theories, experiments, and applications from Class 12 Physics.
The electron was discovered by British physicist J.J. Thomson through his experiments with cathode ray tubes. He demonstrated that cathode rays were negatively charged particles, much lighter than atoms.
By applying electric and magnetic fields to the cathode rays in a vacuum tube, Thomson measured the charge-to-mass ratio (e/m) of the electron, proving it was a universal component of all matter.
Robert Millikan suspended tiny charged oil droplets between two metal electrodes. By balancing gravity and electric forces, he calculated the exact charge of a single electron.
Thomson's formula for the charge-to-mass ratio using electric (E) and magnetic (B) fields:
Value: 1.76 × 10¹¹ C/kg
Charge always occurs in integral multiples of fundamental charge.
Where n is an integer and e = 1.6 × 10⁻¹⁹ C.
The force exerted on an electron moving through an electromagnetic field.
Used in particle accelerators and cyclotrons.
Because electrons have a much smaller wavelength than visible light (De Broglie wavelength), electron microscopes can achieve magnifications up to 10,000,000x, allowing us to see individual atoms.
From the transistors in your smartphone to the screen you are reading this on, the controlled flow of electrons (current) through semiconductors forms the basis of all modern computing.
High-energy linear accelerators use electrons to generate X-rays for medical imaging (CT scans) and precisely target tumors in radiation therapy.