PHYSICS

An electromagnetic field is the field due to the interaction of  electric and magnetic forces on a charged body. An electromagnetic field consists of two closely related components: (i) Electric Field  An electric field is a region around a charged body in which another electric charge experiences a force. It is represented by E and its S.I. unit is newton per coulomb (N C⁻¹) or volt per metre (V m⁻¹). Force on a Current-carrying conductor in a magnetic field  The force, F on the wire is proportional to: (I) Current, (I), flowing in the conductor  (II) the length, (L), of the conductor in the field. (III) the magnetic flux density (B) (IV) the sine of the angle,(θ) between the conductor and the field. When a current-carrying conductor is placed in a magnetic field, it experiences a force. The force is given by: F = BILsin θ Example : The force experienced by a current carrying conductor of length 100cm is 2.0N. Calculate the current in...

A field is a region of space around an object where another object experiences a force. A field cannot normally be seen directly, but its effects can be observed when objects placed within it experience a force. Examples 1. A magnet attracts an iron nail without touching it because there is a magnetic field around the magnet. 2. The Earth attracts objects towards its centre because of its gravitational field. 3. An electrically charged object can attract or repel another charged object because of an electric field.  Types of Fields The major types of fields include: 1. Gravitational field 2. Magnetic field 3. Electric field  Gravitational Field A gravitational field is the region around a mass where another mass experiences a gravitational force. The Earth has a gravitational field around it. This is why objects released above the ground fall towards the Earth. Examples of objects under gravitational field  1. A stone falling to the ground. 2. Rain...

Force is an action  that changes or tends to change the state of rest or of uniform motion in straight line.  The S.I unit of force is the newton (N) . Force is measured using an instrument called a spring balance or Newton meter. Examples of Force i. Pushing a door open. ii. Pulling a bucket from a well. iii. Kicking a football. iv. Lifting a school bag. v. Pushing a table etc   Types of Force The two types of force are: (1) Contact force  (2) Non-contact (or Field) force Contact Force This is a force that acts when objects are physically touching each other. Examples of contact force include: I. Push II. Pull III. Friction: Force that opposes motion between surfaces. IV. Tension: Force acting through a rope or string. B. Non-Contact Force This is a force that acts without physical contact between objects. Examples include: I. Gravitational force: Force that pulls objects towards the Earth. II. Magnetic force: Force of attraction or repulsion between magnets. III. E...

Physics is a branch of pure science that deals with the study of matter, energy, motion, forces and how they interact with one another. Physics helps us to understand many things that happen around us, such as why objects fall to the ground, how vehicles move, how light travels, how electricity works and how sound is produced. A person who studies physics is called a physicist. Branches of Physics Physics is divided into several major branches. They include: 1. Mechanics 2. Waves 3.  Optics 4. Nuclear Physics 5. Electromagnetism 6. Thermodynamics Mechanics : Mechanics is the study of the motion and rest of objects and the forces acting on them. Waves : Waves is the study of how energy moves from one place to another. Optics : Optics is the study of light and how it behaves. Nuclear Physics:   Nuclear physics is the study of the nucleus of an atom and its energy. Electromagnetism : Electromagnetism is the study of the relationship between electricity and magnetism. The...

Energy is the ability to do work. It exists in various forms and can be transferred or transformed from one form to another. Energy is essential in every aspect of life and drives all processes in nature and technology. Types of Energy 1. Mechanical energy 2. Thermal (Heat) energy 3. Chemical energy 4. Electrical energy 5. Nuclear (Atomic) energy 6. Sound energy 7. Light energy       Mechanical energy Mechanical energy is the energy that is possessed by an object due to its motion or due to its position. Types of mechanical energy The two types of mechanical energy are: 1. Kinetic Energy Kinetic energy is the energy of a moving object. The S.I. unit of kinetic energy is joules (J) Formula: K.E. = ½mv² where: m= mass (kg), v = velocity (m/s). Example: (i) What is the Kinetic energy of a 1500 kg car going at a speed of 14 m/s? Solution: K.E. = ½mv² m=1500kg, v=14m/s K.E=½ x 1500 x 14²       = 147,000J (ii) What is the velocity of a 1000 kg car if ...

A vector quantity is a physical quantity that has both magnitude and direction. Vector quantities are essential in understanding and solving problems in physics and engineering as they provide a complete description of physical quantities that involve direction. Examples of Vector Quantities 1. Displacement 2. Velocity 3. Acceleration 4. Force 5. Momentum Applications of Vector Quantities 1. Use for navigation by airplanes and ships to know their displacement and velocity 2. Use in physics to calculate forces in mechanics.  3. Use in Engineering for designing structures with force analysis Assignment Define the following: 1. Displacement 2. Velocity 3. Acceleration 4. Force 5. Momentum

Work is the product of force and the distance moved in the direction of the force. Work is done only when there is displacement in the direction of the applied force. It is a scalar quantity. Work = Force x Distance  Force = mass(m) x acceleration due to gravity (g) Force =mg Work = Force(mg) x Distance (h)           = mgh S.I unit of work is Newton-meter(Nm) or Joule (J) Example 1: A person pushes a box with a force of 50 N over a distance of 5 m in the same direction. How much work is done? Solution: Work = Force x Distance           = 50N x 5m           = 250Nm Example 2: An object is horizontally dragged across the surface by a 100 N force acting parallel to the surface. Find out the amount of work done by the force in moving the object through a distance of 8 m. Solution: Work = Force x Distance           = 100N x 8m           = 800J Example ...

A wave is a disturbance that transfers energy from one point to another without transferring matter. Types of Waves There are two major types of waves, namely: (a) Mechanic waves (b) Electromagnetic waves (a) Mechanical Waves A wave that requires a medium to travel through (e.g., water, air, solids). Examples of mechanical Waves: Sound waves, water waves, seismic waves. Types of mechanical Waves (i) Transverse waves (ii) Longitudinal waves Transverse Waves : In Transverse waves, the particles move perpendicular to the direction of wave propagation (e.g., water waves, light waves). Longitudinal Waves : The particles move parallel to the direction of wave propagation (e.g., sound waves). (b) Electromagnetic Waves They are waves that do not require a medium to travel. They can move through a vacuum. Examples: Light, radio waves, X-rays, microwaves etc Wave Parameters (i) Crest - The highest point on a wave (ii) Trough - The lowest point on a wave (iii) Wavelength (...

             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   ...