PHYSICS

             Refraction of light waves Refraction is the bending of a light ray as it crosses the boundary between two media of different densities thereby causing a change in its direction.  where:           i = angle of incidence            r = angle of refraction           N = normal  As light ray moves from one medium to another, the speed and wavelength of light change but the frequency remains unchanged. The speed of light can change when light travels from one medium to another of different refractive index(optical density) where e= emergent angle                   Laws of refraction  1. The incident ray, the refracted ray, and the normal at the point of incidence all lie on the same plane  2. The ratio of the sine of the angle of incidence to the sine of th...

MODE OF HEAT TRANSFER Heat flows from a body at a higher temperature to another at a lower temperature. The modes of heat transfer are: a.        Conduction b.        Convection c.        Radiation A.       CONDUCTION Conduction of heat is the process by which heat energy is transferred through a material with the average particles of the materials remaining the same. Thermal Conductivity Thermal conductivity is the ability of a metal to conduct heat. where; K          =        Thermal conductivity Q       =        Quantity of heat transferred d        =        Distance between the two isothermal planes A       ...

Real Cubic Expansivity ( γ r ) Real (absolute) cubic expansivity is defined as the actual volume per unit volume per degree rise in temperature when the expansion of the vessel is taken into consideration. Apparent Cubic Expansivity ( γ a ) Apparent cubic expansivity is the increase in volume per unit volume per degree rise in temperature when the expansion of the vessel is not considered. Real Cubic Expansivity ( γ r ) = Apparent Cubic expansivity ( γ a ) + cubic expansivity of the container ( γ c ).                            γ r = γ a + γ c   Example 1. A density glass bottle contains  42.02g   of a liquid at 0 o c and 44.25g at 50 o c. Calculate the real cubic expansivity. (Linear expansivity of glass,  α = 1.0 x 10 -5 k -1 )                             Solution   ...

                       Resources Resources refer to all the materials present in our environment which are used by living things.   Natural Resources:  Natural resources are resources that occur on Earth and are formed through natural processes without human intervention. Humans require many useful things available in nature to live on this planet. Examples of natural resources are air, water, wood, animals, and minerals. When humans use natural things to make a new thing that increases its value, it is known as a man-made resource. Types of Natural Resources There are two types of energy resources: 1. Renewable energy resource    2. Non-renewable energy resources              Renewable resources Renewable resources are those that cannot be depleted. They are always available and can be reused. Examples of renewable energy resources: Sun, Wind, Water, Soil and B...

                     Gravitation  Gravitation  is defined as a natural phenomenon by which all physical bodies attract one another. Gravity: This is   the force that attracts a body towards the centre of the earth.                  Gravitational pull  Gravitational pull is the force of attraction to the earth. The gravitational pull on the moon is about one-sixth of that of the Earth and that is why astronauts seem lighter and need special boots and clothes to walk on the moon                Effects of gravitational pull 1. Gravitational pull affects the weight of an object  2. It helps human beings to stand well on the earth  3. It keeps the planets of the solar system in their positions  4. It helps the moon to keep revolving around the earth  5. It helps in the formation of tides ...

 A solar system  is a system of stars, planets, moons, and other objects, bound together by gravitational orbit.  The solar system is divided into two parts:  1. Inner parts  2. Outer parts  The inner parts consist of the Sun, Mercury, Venus, Earth, and Mars. The outer parts consist of Jupiter, Saturn, Uranus, and Neptune. The two parts are separated by an  asteroid belt.                          Solar system                   The Earth in space  The Earth is the third planet in the solar system that supports life. It has one natural satellite called the  moon. The moon takes about one month to orbit the Earth.                     Parts of the Earth      The three major parts of the earth  1. Lithosphere: The solid part...

Space is the region outside the Earth's atmosphere. Yuri Gagarin was the first person to go to space on April 12, 1961.                      Rocket                 Purpose of space travel  1. To boost international relations  2. To provide a base for scientific research in outer space  3. To provide an alternative power source  4. To discover natural resources on other planets                    Benefits of space travel 1. Space travel helps in weather forecast  2. It helps in predicting natural disasters such as floods, storms, tornadoes, and hurricanes  3. Technological advancements like cell phones, satellite radio and television, GPS navigation in cars, etc  4. Provision of alternative power source eg space solar power  5. It provides data about the Earth and other planets. 6. It...

                         Satellite  A satellite is an object that has been sent into space to collect information or to be part of a communications system. They move in circular paths called orbits around a planet. The moons that orbit the planets in the solar system are the natural satellites. The Earth has one natural satellite. Satellites made by scientists are called Artificial satellites. Examples of artificial satellites are: 1. Sputnik 1: launched by Russia in 1957   2. Explorer 1: launched by USA in 1958  3. Osumi: launched by Japan in 1970  4. Prospero X-3: launched by the UK in 1971 5. SAT 1: launched by Nigeria in 2003 6. COMSAT-1: launched by Nigeria in 2007            Types of Artificial satellites  1. Communication satellites: Used for telecommunication 2. Weather satellites: Used for weather forecast 3. Observation(Surveillance) satel...

                               Shadow  A shadow is an area in which light rays from a source cannot reach                           Types of shadow  There are two types of shadow: 1. Umbra: A region of complete darkness 2. Penumbra: A region of partial darkness                                   Eclipse  An eclipse is a result of a shadow cast by one heavenly body on another                           Types of eclipse  There are two types of eclipse, namely: 1. Eclipse of the sun (Solar eclipse) 2. Eclipse of the moon (Lunar eclipse)                         Solar eclipse  Solar eclipse occ...

The speed of sound is the distance traveled per unit of time by a sound wave as it passes through a material medium. The speed of sound depends on the type of medium in which the sound propagates. The speed of sound in air is about 330m/s.  Speed of sound =Frequency x wavelength                            V= f x  λ Example 1: What is the wavelength of the sound from a tuning fork that vibrates at a frequency of 300Hz in air? (velocity of sound = 330m/s) Solution: Speed of sound =Frequency x wavelength                            V= f x  λ                      330 = 300 x  λ                          λ = 330/300                           λ =...

             Mechanical Advantage (M.A) Mechanical advantage or force ratio is the ability of a machine to overcome a large load through a small effort. M.A has no S.I. unit  Example: A load of 20N is raised by an effort of 4N. Calculate its mechanical advantage. Solution:  Mechanical advantage = Load/Effort M.A = 20/4  M.A = 5                         Velocity ratio (V.R) Velocity ratio is the ratio of the distance moved by the effort to the distance moved by the load at the same time interval. V.R has no S.I. unit  Example: Calculate the velocity ratio of a machine if the distance moved by effort is 5m and that of the load is 2m. Solution:  V.R = distance moved by the effort/ distance moved by the load   V.R = 5/2  V.R = 2.5                 Efficiency of a machine  Work outpu...

A machine  is a device used to overcome load at one end by the application of effort at the other end. It is used to transfer energy from one place to another. A machine that has no friction is called an ideal (perfect) machine. Examples of machines are, pliers, wheelbarrows, screwjack, etc                    Types of machine  The different types of machines are: 1. Lever  2. Pulleys  3. Inclined plane  4. Screw  5. Wheel and axle  6. Wedge  7.  Gear wheels  8. Hydraulic press                                 Lever  A lever is a simple machine consisting of a rigid rod pivoted at a fulcrum. Terms used about lever: 1. Effort: Effort is the force applied  2. Load: Load is the object been lifted  3. Fulcrum: The fulcrum is the point of pivoting.             ...

Sound is a form of energy produced by vibrating bodies. This vibration gives rise to sound waves.                             sound wave                                               Types of sound  The different types of sound are: 1. Music: Music is a combination of regular notes 2. Noise: Noise is a combination of irregular notes                       Production of sound  Sound is produced when a body vibrates. The vibrating body then causes the medium (air, liquid, and solid) around it to also vibrate. Sound requires a material medium for its propagation unlike light                  Transmission of sound  Sound is transmitted through a medium such as air, or water in the...

                 Refraction of light  Refraction is the bending of a light ray as it crosses the boundary between two media of different densities thereby causing a change in its direction                     Laws of refraction  1. The incident ray, the refracted ray, and the normal at the point of incidence all lie on the same plane  2. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media.  The second law is also known as Snell's law                           n= sin i/ sin r  Where n= Refractive index              i= angle of incidence              r= angle of refraction  Example: The angle of incidence is 60° and the angle of refractio...