Energy, Waves, Sound, Light, and Electricity: Physics Fundamentals

Energy

Energy is the capacity of bodies to produce transformations in themselves or other bodies.

Energy Sources

Energy sources are natural resources from which humans can obtain usable energy.

Types of Energy Sources

• Non-renewable: Found in limited quantities and are depleted with use.
• Renewable: Considered inexhaustible as they are continuously renewed.

Energy Principles

• Conservation of Energy: The total energy in the universe remains constant in any process.
• Degradation Principle: With each transformation, energy loses quality and produces new transformations.

Work and Power

Work (W) is done when a constant force (F) is applied to a body, causing a displacement (d) in the same direction as the force: W = F * d.

Power is the rate at which work is done. The SI unit for power is the watt (W), defined as one joule per second (1 J/s). Power (P) = Work (W) / Time (t).

Types of Energy

• Kinetic Energy: The energy possessed by bodies in motion.
• Potential Energy (Gravitational): The energy a body possesses due to its position relative to the Earth's surface.

Mechanical Energy

Conservation of Mechanical Energy: If only conservative forces do work on a body, the sum of its kinetic and potential energy remains constant throughout its trajectory.

Mechanical Machine: A device that receives work from an external force and transmits it to another body.

Efficiency: The ratio of useful work produced by a machine to the work supplied, expressed as a percentage.

Conservative Forces: Forces that do not produce work when the initial and final points are the same, and the work done only depends on the change in mechanical energy.

Waves

A wave is a way of transmitting energy through the propagation of a disturbance.

Wave Classification

• By Nature: Mechanical and electromagnetic.
• By Vibration Direction: Longitudinal and transverse.

Wave Characteristics

• Amplitude
• Wavelength
• Period
• Frequency
• Speed

Acoustics

Acoustics is the branch of physics that studies the nature of sound, how it propagates, and its qualities.

Sound

Sound is a form of energy transmission caused by the vibration of a body. It propagates through mechanical waves and stimulates the ear.

Sound Production

To produce sound, a sound focus, an elastic medium, and a receiver are needed.

Sound waves are longitudinal, meaning the particles of the transmitting medium vibrate in the direction of wave propagation.

Sound Qualities

• Intensity: Corresponds to the sound wave's amplitude (loudness).
• Tone: Determined by the sound frequency (pitch).
• Timbre: Depends on the shape of the sound wave and allows us to distinguish different instruments.

Noise: Vibrations that cause discomfort or injury to the ear.

Optics

Optics is the branch of physics that studies the nature of light, its propagation, and light phenomena.

Light and Objects

• Luminous Objects: Emit their own light.
• Illuminated Objects: Reflect the light they receive.

Electricity and Light

Electricity is a form of energy emitted by luminous objects, propagating through electromagnetic waves and stimulating the eye.

Refractive Index: The ratio of the speed of light in a vacuum to the speed of light in a medium.

Light Phenomena

• Reflection: The change in direction of a light beam when it strikes a surface. It can be specular (smooth surface) or diffuse (irregular surface).
• Refraction: The change in direction of a light ray as it passes from one medium to another.

Laws of Reflection and Refraction

Reflection:

1. The incident ray, the reflected ray, and the normal are in the same plane.
2. The angle of incidence equals the angle of reflection.

Refraction:

1. Snell's Law

Lenses and Mirrors

Mirror: A perfectly polished surface that produces specular reflection (smooth surface) or diffuse reflection (irregular surface).

Lens: A transparent material bounded by a spherical surface and a flat or two spherical surfaces.

• Converging Lenses: Focus light rays.
• Diverging Lenses: Scatter light rays.

Dispersion: The separation of light into its component colors by refraction.