Dickson E. G

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…

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…

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…

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…

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…

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…

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…

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…

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…

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…

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…

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…

Newton’s first law (law of inertia) This law states that “A body continues in its state of rest or uniform motion unless an unbalanced force acts on it”. The mass of a body is a measure of its inertia. Inertia…

Introduction Refraction is the change of direction of light rays as they pass at an angle from one medium to another of different optical densities. Exp. To investigate the path of light through rectangular glass block. Apparatus: – soft-board, white sheet…

Fluid in physics refers to liquids and gases. To study fluid flow we have to make the following assumptions: We consider fluids to be incompressible We assume that they have little or no internal friction or viscosity.   Streamline and…

Introduction: Oersted’s discovery. Hans Christian Oersted discovered the magnetic effect of a current in 1819. The direction of the field is dependent on the direction of the current. This discovery brought about the development of electric bells, electric motors, telephone…

Measuring length using vernier callipers. Vernier callipers is used when higher accuracy in measurement is required and this cannot be done using a metre rule. Vernier callipers has two scales; main scale and vernier scale. Outside jaws are used to…

Work done per unit charge is called electrical potential. Current is the flow of charge. For current to be continuous, potential difference between the two points must be sustained. Sources of continuous currents. In this process work is continuously done…

Some substances get charged when rubbed against other substances i.e. nylon, plastic, paper etc. the charge acquired stays within the body i.e. it does not move and therefore known as electrostatic charge or static electricity. The law of charges –…