★ MOTION ★
Motion - Refers to a change in the position of a body (E.g., object) from a Reference Point
Reference Point - Any point in space used for comparison to determine whether a body is in motion or not
A body is in motion when it travels toward or away from a reference point
Distance - Length traveled by a body; scalar quantity; has magnitude but no direction
Displacement - Shortest straight line distance from the initial position to the final position of a body; can be defined as the change in the horizontal position of a body
Speed/Velocity - Time interval; Scalar and Vector quantity
Acceleration - When the body changes its speed, direction, or both

★ WAVES ★
Wave - Disturbance that moves from one place to another through a vacuum or a material called a medium
As the wave propagates, it carries energy away from the source
a.) Wave pulse - Single Disturbance b.) Wave train - Series of Disturbances
1. Transverse Waves - When the direction of motion of the particles of the medium is perpendicular to the direction of propagation of the wave (E.g., Rope and spring waves)
2. Longitudinal Waves - Travels in a direction parallel to the direction of motion of the particles of the medium; also a region where the particles are compressed together (E.g., Sound waves)
• Compression – Region where particles are pressed together
• Rarefaction – Region where particles are stretched
Mechanical Waves - Waves that require a medium, which can be a solid, liquid, or gas (E.g., Sound waves, Water waves, Seismic Waves from earthquakes)
Electromagnetic Waves - Propagate with or without a medium (E.g., Gamma-ray, X-ray, Ultraviolet ray, infrared ray, microwave, and radio wave)

★ LIGHT ★
THEORIES ABOUT LIGHT:
1. Particle Theory of Light - Formed in 1704 by Isaac Newton; light consists of particles called corpuscles shooting out like tiny bullets from a source and traveling in a straight line through space
2. Wave Theory of Light - Formed by Christiaan Huygens to explain light propagation; light is a train of waves similar to those that form when an object is dropped into a pool of water
3. Electromagnetic Wave Theory - Proposed by James Clerk Maxwell who predicted the existence of EM waves with a constant speed of propagation

Double Slit Experiment - Performed by Thomas Young that showed the interference of light
Robert Hooke - Experiment on colors
Simeon Denis Poisson - Experiment on diffraction; strongly supported the wave theory

Light was eventually proven to be an EM wave confirmed by Heinrich Hertz

Photoelectric Effect - When light with sufficient energy strikes a photosensitive metal surface, electrons are emitted
Quantum Theory - Proposed by Max Planck in 1900 and Albert Einstein in 1905; assumes light energy is radiated in discrete packets or bundles called photons or quanta

CHARACTERISTICS OF LIGHT:
Colors of Light - World without light would be devoid of colors; colors allow us to see, distinguish, and appreciate everything around us; White light is a combination of all colors of visible light

When white light, passes through a prism, it spreads out into a band of colors called a spectrum

Dispersion - Splitting of white light into its components

Brightness of Light - Distinguishes light of a certain wavelength/frequency from others

FOUR MEASURABLE QUANTITIES OF LIGHT:
Luminous Flux - Amount of energy per unit of time that radiates from a light source in all directions; SI unit: lumen (lm)
Luminous Efficacy - Measure of how well a source radiates light; can be determined by dividing Luminous Flux by power; a higher efficacy means more energy is radiated than what is consumed; expressed in watts (w)
Luminous Intensity - Refers to the amount of energy per unit of time that radiates from a light source in a certain direction; SI unit: candela (cd)

Light with higher frequency (shorter wavelength) carries greater energy

Luminance - Luminous intensity that is reflected from, emitted from, or passing through a source per unit area; unit of measuring: per square meter (cd/m²)
Illuminance - Amount of light (Luminous Flux) that falls on a surface per unit area; SI unit: lux (lx)

★ HEAT ★
INTERNAL ENERGY AND TEMPERATURE:
Internal Energy - Total energy of particles in a body; this energy includes both kinetic and potential energy
Temperature - Defined in terms of the average kinetic energy of the particles in a body
Heat - Energy transit from one body to another

Kinetic energy is due to the movement within and between particles
Potential energy is due to the relative position of the particles

TYPES OF POTENTIAL ENERGY:
Gravitational Potential Energy – Energy stored in an object because of where it is placed; found in objects some height off the ground
Elastic Potential Energy – Energy stored by the forces within a distorted elastic object; found in rubber bands or springs
Chemical Potential Energy – Stored in the bonds between atoms and molecules

HEAT TRANSFER:
Heat Transfer - Occurs solely due to the temperature difference between two bodies

MODES OF HEAT TRANSFER:
Conduction - Occurs through direct contact of two objects with different temperature
Convection - Heat can be transferred through the movement of fluids (liquids and gases)
Radiation - Heat transfer through space is possible via electromagnetic waves; energy transferred is sometimes called radiant energy

★ ELECTRICITY ★
Static Electricity - Common phenomenon where the interaction between charges at rest

Thales of Miletus - Ancient Greek mathematician; first person who observed that when amber is rubbed with animal fur attracts light objects such as feathers
Electricity - Derived from the Greek word for amber, electron; English physician William Gilbert observed that many substances can be electrified; he called these substances electricus meaning “like amber”

Conductors are materials where electric charges can flow easily
Insulators are materials where electric charges move with great resistance

BASIC LAW OF ELECTROSTATICS:
Like charges repel each other and unlike charges attract each other
Bodies with the same charges repel each other and oppositely charged bodies attract each other

THE PROCESS OF CHARGING:
Charging by rubbing or friction - Rubbing two neutral objects against each other may allow electrons to transfer between them; the object that loses electrons becomes positively charged and the object that gains electrons becomes negatively charged

Charging by contact - A neutral object also acquires a charge when it touches a charged object

Charging by induction - Involves a charged object placed near, but not touching a neutral object

Grounding - If an object holds a very large amount of electric charges, it can pose hazards; it is important to provide a pathway for unwanted excess charges to leave an object