RESISTIVITY AND CONDUCTIVITY The resistance of a wire maintain at a constant temperature is related to its length L and its cross-sectional area (A) by the expression R = ρl A Where ρ is a constant known as resistivity of the material (its unit is ohm-metre, Ωm) ρ = RA l R = resistance, A […]
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DEFINITION OF SIMPLE TERMS Electrolysis – Is the process whereby a liquid conducts electricity by the movement of positive and negative ions within the liquid while undergoing chemical changes. Electrolytes – Are liquid, which allows the electricity through them is called electrolytes. Such electricity is salt solutions, alkalis and dilute acids (acidulated water). Non-Electrolytes –
ELECTRIC CIRCUIT Electric current is simply electric charge in motion. Electric cells are chemical devices, which are capable of causing an electric current to flow. This produces electric force, which pushes the current along. Electrons flow from the negative terminal or cathode of the cell to the positive terminal or anode TYPES OF ELECTRIC CELLS
An electric field is a region of space which surrounds a system of electric charges. Electrical forces will act on any electric charge which is placed within the region. Electric field is a vector quantity. The direction of the filed can be determined using a test charge (a small positive charge) Fundamental Law of Electrostatics
INTRODUCTION Gravitational field is a region or space around a mass in which the gravitational force of the mass can be felt. Gravitation is the force of attraction exerted by a body on all other bodies in the universe. Gravitational force act between all masses and hold together planets, stars and galaxies. Each mass has
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DEFINITION AND CONCEPT Electromagnetic waves are produced by electromagnetic vibrations. Electromagnetic waves have electrical origin and the ability to travel in vacuum. So, electromagnetic waves are regarded as a combination of traveling electric and magnetic forces which vary in value and are directed at right angles to each other and to the direction of travel.
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Sound energy is produced when an object vibrates. The sound vibrations cause waves of pressure that travel through a medium, such as air, water, wood or metal. Sound energy is a form of mechanical energy. Examples of Sound Energy An air conditioning fan An airplane taking off A ballerina dancing in toe shoes A balloon
Physics has several applications on health, technology & engineering, agriculture and applied sciences. As a results, below are some of the aspects/careers related to physics. IN HEALTH We have: Human medicine and surgery Nursing & midwives Radiotherapy Pharmacology Physiology Anaesthesia Veterinary etc. IN ENGINEERING We have: Electrical engineering Electronic engineering Mechanical engineering Aeronautic engineering
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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
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
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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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 When the wire is moved up the galvanometer deflects in one direction then the opposite direction when moved
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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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Introduction 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 a constant speed along a curved path of constant radius. When acceleration (variation of velocities)
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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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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
What is heat?. Heat is a form of energy that flows from one body to another due to temperature differences between them. Heat capacity Heat capacity is defined as the quantity of heat required to raise the temperature of a given mass of a substance by one degree Celsius or one Kelvin. It is denoted
When current flows, electrical energy is transformed into other forms of energy i.e. light, mechanical and chemical changes. Factors affecting electrical heating Energy dissipated by current or work done as current flows depends on, a) Current b) Resistance c) Time This formula summarizes these factors as, E = I2 R t, E = I V
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Electric fields An electric field is the space around a charged body where another charged body would be acted on by a force. These fields are represented by lines of force. This line of force also called an electric flux line points in the direction of the force. Electric field patterns Just like in
Electric potential difference and electric current Electric current: Electric potential difference (p. d) is defined as the work done per unit charge in moving charge from one point to another. It is measured in volts. Electric current is the rate of flow of charge. P. d is measured using a voltmeter while current is measured
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