Notes, summaries, assignments, exams, and problems for Physics

Electromagnetic Wave Fundamentals

An electromagnetic wave is a disturbance that propagates through space due to the simultaneous oscillation of electric and magnetic fields. Unlike mechanical waves, they do not require a medium for propagation and can travel through a vacuum.

Properties of Electromagnetic Waves:

• They travel at the speed of light (c) in a vacuum (approximately 3 x 10⁸ m/s).
• They exhibit typical wave properties, such as interference and diffraction.
• Wavelength (λ) and frequency (f) are related by the equation: c = λf.

Examples include: visible light, radio waves, TV waves, microwaves, and X-rays.

The Speed of Light in Vacuum

The propagation speed (c) of electromagnetic waves in a vacuum is calculated using the formula:

c = 1 / √(

Light Source

A light source is an object that emits light. There are natural light sources and artificial light sources. Examples of natural light sources include the Sun and stars, while an example of an artificial light source is a light bulb.

Luminous Bodies

Luminous bodies possess the characteristic of emitting light themselves, such as the Sun or the flame of a candle.

Illuminated Bodies

Illuminated bodies do not produce light but receive it from another body and are able to reflect it. Examples include the Moon, a desk, or a wall.

Opaque Bodies

Opaque bodies do not allow light to pass through them. Examples include a wall or a table.

Translucent Bodies

Translucent bodies allow light to pass through partially, but the light is diffused so that... Continue reading "Understanding Light: Properties, Reflection, and Mirrors" »

Understanding Solar Radiation

Direct radiation: Solar radiation received directly from the sun without being scattered by the atmosphere.

Diffuse radiation: Solar radiation received after its direction has been changed due to reflection and refraction in the atmosphere.

Total radiation is the sum of direct and diffuse radiation at the surface.

Solar Constant

The solar constant is the amount of energy received per unit time on a unit area perpendicular to the sun's direction at Earth's mean distance, outside the atmosphere. The currently accepted value is: S = 1.94 Ly min^-1 = 1368 W/m²

Absorption, Reflection, and Transmission

When radiation strikes a body, it can be absorbed, reflected, or transmitted. The ratio is: e + r + t = 1, where:

• e = absorptivity
• r

Physical science studies the properties of matter and energy, considering the attributes that can be measured. Physics is an empirical science. All that we know of the physical world and the principles that govern its behavior has been learned through the observation of natural phenomena. The ultimate test of any physical theory is its agreement with observations and measurements. Physics is, therefore, essentially a science of measurement. Examples include matter, energy, measurement, and observation.

Key Concepts in Physics

• Matter: The substance that makes up the physical universe, occupying space and existing in many forms perceivable by the senses.
• Empirical: Based solely on observation and factual experience.

Branches of Physics

• Classical Physics:

Understanding Temperature and Heat

Temperature: A measure of the average kinetic energy of the particles in a substance, perceived through our sense of touch as hot or cold. It reflects the internal energy level of a body.

Heat Transfer Methods

Heat can be transferred through three primary methods:

• Conduction: Heat transfer through direct contact.
• Convection: Heat transfer through the movement of fluids (liquids or gases).
• Radiation: Heat transfer through electromagnetic waves.

Units of Heat

• Calorie: The amount of heat required to raise the temperature of one gram of water by one degree Celsius.
• BTU (British Thermal Unit): The amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Thermal Expansion

• Linear Expansion:

Electric Field Fundamentals

5.a) Charged Particle Movement and Energy Changes

When a charged particle moves in an electric field, if the electric force (F_e) is conservative, the change in mechanical energy (ΔEM) is zero. This implies an inverse relationship between kinetic energy (Ec) and potential energy (Ep): if Ec increases, Ep decreases, and vice versa.

If a particle's speed decreases upon entering an electric field, its charge is negative. Conversely, if its speed increases, its charge is positive.

5.b) Work Done by Magnetic Fields on Charges

No work is performed by a magnetic field on a charged particle. A magnetic field generates a magnetic force that is always perpendicular to the path of the charged particle, meaning it does no work.

6.

Physics Concepts

Motion, Forces, and Laws

Motion

MUA
V = V₀ + a * t
D = |ee₀| = V₀ * t + 1/2 * a * t²

Forces

Sum of Concurrent Forces
F_R = √(F₁² + F₂² - 2 * F₁ * F₂ * cos(alpha))
Decomposition of Forces
F_x = F * cos(?)
F_y = F * sin(?)
Deformation (Hooke's Law)
L = l₀
F = K * Δl

Newton's Laws of Motion

1st Law (Inertia)
∑F = 0
2nd Law (Acceleration)
∑F = m * a
3rd Law (Action-Reaction)
For every action, there is an equal and opposite reaction.

Sum of Forces (Different Directions)

Concurrent Forces
R = √(F₁² + F₂²)
Parallel Forces
R = F₁ + F₂

Centripetal Force

F_c = m * a_n = m * v² / r = m * ω² * r

Other

P = m * g
F_r = μ * N

Force Interactions and Types

A force is an interaction between two bodies: the force exerted and the recipient.

• Weight: Gravitational force on

Types of Waves

Mechanical Waves

These waves require a material medium for transmission. There are two main types:

• Longitudinal Waves: These waves travel parallel to the direction of propagation.
• Transverse Waves: These waves travel perpendicular to the direction of propagation, such as the waves on a vibrating guitar string.

Electromagnetic Waves

These waves do not require a physical medium for transmission.

Examples of Waves:

• Sound Waves: Acoustic waves.
• Seismic Waves: Caused by Earth's activity.
• Electromagnetic Waves: Related to electromagnetic forces.
• Wave Power: Generated by wind.
• Mechanical Waves: Produced by mechanical energy.
• Radio Waves: Propagate through the air.

Reflection of Light

The incident ray, the normal, and the reflected ray all lie in the... Continue reading "Light and Wave Phenomena" »

Metallography: The Science of Measurement

Metallography is the science that studies measurement, focusing on magnitudes like time, length, mass, and strength.

Units of measurement include SI and SA units. Instruments like rulers and calipers are used for measurement.

Specific rules ensure correct measurement, and proper instructions are necessary for using measuring instruments effectively.

Measurement Fundamentals

Measurement involves determining a numerical value for a quantity, such as length or mass.

Factors influencing measurement include the instrument's precision, the operator's skill, and environmental conditions.

Types of Measurement

• Direct Measurement: Obtaining a value immediately through instrument reading.
• Indirect Measurement: Requiring

Pressure and Fluids

What is Pressure?

Sometimes the effect of force also depends on the size of the surface on which it operates. The pressure takes into account two variables: the strength and the surface. Pressure occurs when a force acts on a unit area.

Pressure is defined as the force acting on a unit area (p = F / S). The SI unit is the newton per square meter (N/m²), which is called the pascal and whose symbol is Pa (1 Pa = 1N / 1 m²). Pressure is a scalar because it acts with an equal numerical value in all directions.

What are Fluids?

The term fluid includes both liquids and gases, and their properties are:

1. They do not have their own shape.
2. They take the form of the container that contains them.

This is because the particles that make up the... Continue reading "Understanding Fluid Pressure and Hydrostatics" »