Notes

Introduction to Radioactivity – Radioactivity was discovered by Henri Becquerel in 1869. In 1898, Marie and Pierre Curie succeeded in chemically isolating two radioactive elements, Polonium (z=84) and Radium (z=88).Radioactivity or radioactive decay is the spontaneous disintegration of unstable nuclides to form stable ones with…

Introduction to Photoelectric Effect – Photoelectric effect was discovered by Heinrich Hertzin 1887.Photoelectric effect is a phenomenon in which electrons are emitted from the surface of a substance when certain electromagnetic radiation falls on it.– Metal surfaces require ultra-violet radiation…

What are X-rays? – X-rays were discovered by a German scientist namedRoentgen in 1985.– They can pass through most substances including soft tissues of the body but not through bones and most metals.– They were named X-rays meaning ‘unknown rays’.…

What is a Cathode Ray? These are streams of electrons emitted at the cathode of an evacuated tube containing an anode and a cathode. Production of Cathode Rays They are produced by a set up called a discharge tube where a high…

Introduction to Main Electricity – Mains electricity comes from a power station and its current is the alternating current which can either be stepped up or down by a transformer. A.c is produced when a conductor is rotated in a magnetic…

Introduction to Electromagnetic Induction Electromagnetism is the effect resulting from the interaction between an electric current and a magnetic field. This effect brings about induced electromagnetic force (e.m.f) and the resulting current is called induced current. Experiments on electromagnetic induction Consider…

Introduction to Electromagnetic Spectrum Electromagnetic spectrum is a continuum of all electromagnetic waves arranged according to frequency and wavelength. It includes visible light, ultra-violet rays, microwaves, X-rays, radio waves and gamma rays. Electromagnetic waves are produced when electrically charged particles oscillate…