March 26, 2012
March 11, 2012
1) An object will fall to the surface of the earth because it is pulled down by the force of gravity.
2) The pull or force of gravity also known as Earth's Gravitational Force
3) When an object falls without encountering any resistance and under the force of gravity only, the object is said to be free falling object.
February 8, 2012
|GRAVITATIONAL POTENTIAL ENERGY, PE = mass x gravity x height|
|ELASTICS POTENTIAL ENERGY , PE = (1/2) force ( extension)2|
|POTENTIAL ENERGY DEPENDS ON POSITION OF OBJECT. THE HIGHER THE POSITION OF OBJECT FROM GROUND, THE BIGGER THE POTENTIAL ENERGY.|
August 1, 2011
CHAPTER SIX (WAVES)
MEANING / DEFINITION
Wave motion carries energy from one place to another place in a medium without the transfer of the particles along the medium.
A wavefront is a line or plane where the vibrations of every point on it are in phase
A wave in which the vibration of particles in the medium is at perpendicular to the direction of propagation of the wave.
A wave in which the vibration of particles in the medium is parallel to the direction of propagation of the wave.
The maximum displacement from its equilibrium position.
The time taken to make one complete oscillation
The number of complete oscillations made by a vibrating system in one second
One complete oscillation
Satu ayunan lengkap
A complete oscillation may be referred as the movement of a vibrating system from one extreme position to the other and back to the same position.
The wavelength is the distance between successive points of the same phase in a wave.
Damping occurs when an oscillating system loses energy due to frictional forces.
Forced oscillation occurs when a system oscillates under the influence of an external driving force.
The frequency of a system when it oscillates freely.
Resonance occurs when a system oscillates at the maximum amplitude when the driving frequency is equal to the natural frequency of the system.
Reflection of waves
Reflection of waves is the change in direction of propagation when a wave strikes an obstacle.
The waves moving towards an obstacle.
The wave which has undergone a change in direction of propagation after reflection.
Angle of incidence
The angle between the direction of propagation of the incident wave and the normal
Angle of reflection
The angle between the direction of propagation of reflected wave and the normal.
Law of Reflection
The angle of incidence is equal to the angle of reflection
Refraction of waves
Refraction is the change of direction of propagation when the speed of a wave changes as it moves from one medium to another
Diffraction of wave
Diffraction of waves is the spreading of waves as they pass through an aperture or around the edge of an obstacle
Principle of superposition
The sum of the displacements of all the component waves at the point.
Waves of the same frequency and are in phase.
Superposition of two coherent waves constructively or destructively
Occurs when two waves that are in phase superimpose
to produce a wave with crests and troughs of maximum amplitude.
Occurs when two waves that are out of phase superimpose to produce zero resultant amplitude
A point where constructive interference occurs.
A point where destructive interference occurs.
Sounds are longitudinal waves produced by vibrations such as the vibrations of the diaphragm of a loudspeaker, guitar string and tuning fork.
The intensity of a sound as heard by an observer (depends on the amplitude of the sound)
The pitch of the sound is an indication of the sharpness of a sound (depends on the frequency of the sound)
Sound Navigation and Ranging (SONAR) is a system used to detect underwater objects or to determine the depth of the water by means of an echo.
Electromagnetic waves are propagating waves in space with electric and magnetic components.
CHAPTER SEVEN (ELECTRICITY)
MEANING / DEFINITION
Current is the rate of flow of electric charge
SI unit of current
A unit of charge
An electric field is a region where an electric force acts on a particle with an electric charge.
Potential difference is defined as the work done to move a unit of charge from one point to another in an electric field.
The electric current flowing through a conductor is directly proportional to the potential difference across the ends of the conductor, if the temperature and other physical dimensions remain constant.
Material which obey Ohm’s Law
Non Ohmic Conductor
Konduktor bukan Ohm
Material which do not obey Ohm’s Law
Resistance is defined as (potential difference)/(current)
The effective resistance is the combined resistance in the circuit.
Electromotive Force (e.m.f)
Daya gerak elektrik (d.g.e.)
The total energy supplied by a cell when one unit of charge flows through the cell.
The resistance within a cell due to its electrolyte or electrodes
Energy supplied by a source of electricity (cell / battery) when current flows in a closed circuit.
Power is the rate of transfer of electrical energy
The power rating of an appliance denotes the rate at which it consumes electrical energy at a certain voltage
CHAPTER EIGHT (ELECTROMAGNETISM)
MEANING / DEFINITION
An electromagnet is a device in which magnetism is produced by an electric current. It is a temperory magnet. It acts as a magnet when the current is flow and ceases to be a magnet when the current is switched off.
A magnetic field is a region in which a magnetic materials experiences a force.
The resultant field produced when a straight wire carries a current in a uniform magnetic field.
Direct current motor
Motor arus terus
A direct current motor is used to convert electrical energy into rotational kinetic energy.
The production of an electromotive force in a conductor due to a changing magnetic flux.
An emf produced in a conductor when there is a changing magnetic flux or cutting of magnetic flux by the conductor
Induced current is produced in a circuit when there is a changing magnetic flux or cutting of magnetic flux by a conductor
The magnitude of the induced e.m.f is directly proportional to the rate at which a conductor cuts through the magnetic flux.
Lenz's Law state that an induced electric current always flows in such a direction as to oppose the change in magnetic flux.
Current which flows in one direction.
Arus ulang alik
Current which flows back and forth in two opposite directions
A device which steps up or steps down the voltage of an alternating current.
Transformer injak naik
A transformer that steps up voltage
Transformer injak turun
A transformer that steps down voltage
A transformer where the output power is equal to the input power and the efficiency is 100%
Transmission of electricity
The transmission of electricity from the power station to consumers (industries and residential areas) by electric cables
National Grid Network
Rangkaian Grid Nasional
The national grid is a network of electrical cables connecting electrical power stations to consumers of electricity.
CHAPTER NINE (ELECTRONICS)
MEANING / DEFINITION
A process of emitting electrons from a hot metal surface.
A beam of fast moving, high energy electrons
Materials whose resistance is between those of good conductors and good insulators.
The process of adding a small amount of impurities into the semiconductors.
Semiconductor where the majority charge carriers are free electrons
Semiconductor where the majority charge carriers are holes
A p-n junction device which conducts current in one direction only
Pincang ke hadapan
A diode is forward biased when the p-end is connected to the positive terminal of the battery and the n-end is connected to the negative terminal of the battery.
A diode is reverse biased when the p-end is connected to the negative terminal of the battery and the n-end is connected to the positive terminal of the battery.
To convert alternating current into direct current using diodes
Rektifikasi separuh gelombang
The process of rectification using a diode which allows current flow in half of a cycle.
Rektifikasi penuh gelombang
The process of rectification using four diodes to allow current to flow in a complete cycle and in the same direction.
A capacitor that is used to smoothen the output voltage of a rectification process
A transistor which consists of a layer of p-type semiconductor sandwiched between two layers of n-type semiconductors.
A transistor which consists of a layer of n-type semiconductor sandwiched between two layers of p-type semiconductors.
A logic gate is an electronic switch with one or more inputs and only one output.
A truth table shows the results of every possible output given every possible input.
A logic gate where the output is 1 only when both inputs are 1
A logic gate that inverts the input
A logic gate where the Output is 1 except when both inputs are 0
CHAPTER TEN (RADIOACTIVITY)
MEANING / DEFINITION
The small core of the atoms which contains the protons and neutrons
Protons and neutrons
Proton number, Z
The number of protons in the nucleus of an atom
Nucleon number, A
The total number of protons and neutrons in an atom.
A nuclide is one type of nucleus with a particular proton number and a particular nucleon number.
Atoms of an element which have the same proton number but different nucleon numbers
Isotopes with unstable nuclei
Radioactivity is the spontaneous disintegration of unstable nucleus into a more stable nucleus with the random emission of radiation.
Radioactive decay is a process where an unstable nucleus becomes a more stable nucleus by emitting radiation
A radioactive decay where an alpha particle is emitted
A radioactive decay where a beta particle is emitted
A radioactive decay where gamma rays are emitted
The time taken for mass or activity of a radioactive substance to become half its original value
Atomic mass unit (a.m.u)
Unit jisim atom
The atomic mass unit (a.m.u) is used to measure the masses of atomic particles.
A process involving the splitting of a heavy nucleus into two lighter nuclei and several neutrons at the same time
Tindak balas berantai
A chain reaction is a self-sustaining reaction in which the neutrons produced in a reaction can initiate another similar reaction.
Nuclear fusion is the combining of two lighter nuclei to form a heavier nucleus
A nuclear reactor produces tremendous amount of energy through nuclear fission.