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

Understanding Magnetic Force

The fundamental principle behind all magnetic phenomena is that a force arises between electric charges when they are in motion. This force is known as magnetic force.

Key Discoveries and Experiments

Oersted's Discovery (1820)

In 1820, Hans Christian Oersted accidentally discovered that an electric current could produce a magnetic field, deflecting the needle of a compass.

Faraday's Power Line (1831)

Michael Faraday's concept of the 'power line' explained the behavior of forces acting at a distance.

Properties of Magnetic Field Lines

The properties of magnetic field lines are:

1. All magnetic field lines run from the north to the south magnetic pole.
2. The magnetic field strength is directly proportional to the number of field

... Continue reading "Magnetic Force: History, Properties, and Key Experiments" »

Current Density

The electric current density is a vector quantity representing power per unit area. It relates to current as:

• I is the electric current in amperes (A).
• j is the current density in amperes per square meter (Am^-2).
• S is the area in square meters (m²).

Isolated Point Charges

Current density relates to charge carriers (electrons, holes, ions) by:

Where:

• n_i is the concentration of carrier i.
• q_i is the electric charge of carrier i.
• v_i is the average velocity of carrier i in the volume.

Electromotive Force (EMF)

Electromotive force maintains a potential difference in an open circuit or produces current in a closed circuit. It's a generator characteristic, explained by an electric field Ξ, where defines the EMF.

EMF is the work done to move a... Continue reading "Understanding Current Density and Electromotive Force" »

Uniform Rectilinear Motion

... Continue reading "Understanding Uniform Rectilinear Motion: Concepts and Equations" »

Understanding Wave Motion

Wave motion is a form of energy transmission that is not accompanied by the transport of matter. It is the propagation of a vibration, i.e., the propagation of movement around the equilibrium position of a body.

A wave is the position taken at each instant by the disturbance that has occurred.

Types of Waves

• Mechanical waves originate when a disturbance occurs in an elastic medium, which would not exist without the spread.
• Electromagnetic waves, although they may be transmitted through certain media, do not necessarily need an elastic medium and can propagate in a vacuum.

Wave Characteristics

• In longitudinal waves, the vibrations of particles around their equilibrium point occur in the same direction in which the wave propagates.

... Continue reading "Understanding Wave Motion: Types, Properties, and Sound" »

Motion and Kinematics

Reference Systems and Motion

A reference system is a point from which the movement of a body is observed. The temporal reference system indicates the starting time for studying a movement, represented by the letter T, with the SI unit of seconds (s). A body's movement involves changes in its position over time relative to a spatial and temporal reference system. Kinematics is the branch of physics that studies motion.

Position and Trajectory

Position indicates a body's location with respect to a reference system at a given time. The trajectory is the set of points through which a body moves concerning a reference system. Trajectories can be classified as:

• Rectilinear motion: The trajectory is a straight line.
• Curvilinear motion:

... Continue reading "Motion, Forces, and Dynamics: A Comprehensive Overview" »

Physics Problems: Work, Energy, and Forces

This document presents a series of physics problems focusing on concepts of work, energy, and forces, followed by their detailed solutions. These exercises are designed to reinforce understanding of fundamental mechanics principles.

Problem Statements

• Problem 1: Work as a Scalar or Vector?

  Is work a vector or a scalar quantity?

• Problem 2: Negative Work Scenarios

  Can work be negative? If so, in what cases does it occur?

• Problem 3: When is Energy Not Conserved?

  In what cases is mechanical energy not conserved?

• Problem 4: Work Done on a Box

  A box weighing 900 [N] rests on the ground. Calculate the work required to move it at a constant speed:

  • a) Moving Horizontally Against Friction

    4 [m] on the floor against a friction

... Continue reading "Physics Problem Set: Work, Energy, and Force Calculations" »

Photogrammetry and Imaging Fundamentals

• Photography is a complete representation of an object that provides metric information. False.
• Photogrammetry allows us to reconstruct a three-dimensional model from a photograph of an object. False.
• To perform photogrammetric restitution, it is necessary to orient photographs to their position at the time of the shot. True.
• A photogrammetric document provides qualitative exploitation. True.
• Photogrammetry is a method suitable for small tracts of land. False.
• To perform photogrammetric restitution, it is necessary to have a photograph of the object to be restituted. False.
• The ideal photogrammetric camera is one that allows the continuous and accurate capture of an image. False.

Camera and Image Quality

• The aerial

... Continue reading "Essential Photogrammetry and Imaging Facts" »

Il Gesu: A Precursor to Baroque

The construction of Il Gesu began in 1527 but faced delays due to financial constraints. It was finally consecrated in 1685 by Andrea Pozzo, although it remained unfinished. Andrea Pozzo painted the dome on canvas, where the roof is flat.

The Facade

The facade bears a striking resemblance to that of the Church of the Gesu. The lower section features a similar joint, with notable entry columns. There is an interplay of inputs and outputs, verticality, and decorative plates with angles, which are more pronounced. These plates would become a defining feature of the Baroque style. On the second level, columns are positioned in front of the pillars seen in the Gesu. The pediment introduces a decorative element, departing... Continue reading "Baroque and Renaissance Architecture: Saint Peter's Basilica and Il Gesu" »

Understanding Energy: Definition and Units

Energy is the ability of bodies to perform work. Key formulas and conversions include:

• E = P * t (Energy = Power * time)
• E = Q * U (Energy = Charge * Voltage)

Common units of energy are: 1 Watt-hour (Wh) and 1 Joule (J). Important conversions are:

• 1 Joule (J) = 0.239 calories (cal)
• 1 calorie (cal) = 4.18 Joules (J)
• 1 Watt-hour (Wh) = 3,600 Joules (J)

Forms of Energy

Kinetic Energy

The energy possessed by a body due to its motion, depending on its speed and mass.

Potential Energy

Stored energy, often due to a body's position or state, such as its height above a reference point (e.g., the ground).

Mechanical Energy

The sum of kinetic and potential energy in a system, often associated with the motion or position... Continue reading "Energy Fundamentals: Forms, Transformations, and Key Sources" »

1. Waves and Communication

Electromagnetic waves are transmitted through various communication systems, such as radio, telephone, or even our voice. A wave is a disturbance that travels through space without transferring material, but energy.

Features of Waves

• The time it takes for one complete oscillation is called the period.
• The number of oscillations per second is called frequency (f) and equals the inverse of the period: f = 1 / T. It is measured in s^-1, also known as Hertz (Hz).
• The distance between two peaks (the highest points of a wave) or two valleys (the lowest points of a wave) is the wavelength (λ). The longer the wavelength, the lower its frequency.
• The amplitude (A) is the maximum distance a particle displaced by the wave reaches

... Continue reading "Understanding Waves: Communication, Types, and the Electromagnetic Spectrum" »