Form 4

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…

Introduction to Floating and Sinking – Any object in a liquid whether floating or submerged experiences an upward force from the liquid; the force is known as upthrust force.– Upthrust force is also known as buoyant force and is denoted by letter ‘u’.…

What is Uniform Cicular Motion? Circular motion is the motion of bodies travelling in circular paths. Uniform circular motion occurs when the speed of a body moving in a circular path is constant.This can be defined as motion of an object at…

What is a Lens? A lens is conventionally defined as a piece of glass which is used to focus or change the direction of a beam of light passing through it.They are mainly made of glass or plastic. Lens are…