Dickson Phy

Physics

ELECTRONICS

Conductors, insulators and semi-conductors i) An insulatoris a material or object which resists flow of heat (thermal insulator) or electrical charges (electrical insulators). Examples are paraffin, wood, rubber, plastics etc. ii) Conductorsare materials that contain free electrons which carry an electrical charge from one point to another. Examples are metals and non-metals like carbon, graphite …

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Physics

RADIOACTIVITY

Introduction 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 the emission of radiation. Unstable nuclides continue to disintegrate until a …

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Physics

PHOTOELECTRIC EFFECT

Photoelectric effect was discovered by Heinrich Hertz in 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 while caesium oxide needs a visible light i.e. optical spectrum (sunlight).   Work function A minimum amount of …

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Physics

ELECTROMAGNETIC SPECTRUM

What is Electromagnetic?. 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 or change energy in some way. The waves travel perpendicularly to both electric and magnetic …

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Physics

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’.   Archimedes’ principle Floating and Sinking Archimedes, a Greek scientist carried out first experiments to measure upthrust on …

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Physics

THE GAS LAWS

Pressure law  This law states that “the pressure of a fixed mass of a gas is directly proportional to the absolute temperature if the volume is kept constant”. The comparison between Kelvin scale and degrees Celsius is given by; θ0 = (273 + θ) K, and T (K) = (T – 273) 0C. Examples A …

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