Notes, summaries, assignments, exams, and exercises for Physics for Baccalaureate

Forces Between Flows of Ampere Straight and Parallel: Definition

A conductor carrying an electric current creates a point around a magnetic field, which is directly proportional to the intensity of the current through the conductor I, and inversely proportional to the distance d from the conductor to the point under consideration.

If you place a conductor carrying a current in a magnetic field, the field exerts an interaction on it that depends upon the value of field strength B, the current I flowing through the conductor, and the length of the conductor l. The direction of F is perpendicular to the plane determined by the vectors B and l. The meaning of the interaction is fixed by the right-hand rule.

When two conductors carrying electric currents...

Coulomb's Law and Electric Force

Coulomb's Law: The electric force with which two resting charges, q₁ and q₂, attract or repel each other is directly proportional to the product of the charges and inversely proportional to the square of the distance d (or r) that separates them.

The force is a vector unit according to the direction of the charges. The constant k has a numerical value of 8.9874 × 10⁹. The unit of electric charge is the Coulomb (C): The Coulomb is the positive charge q which, when placed in a vacuum at a distance of 1 meter from another identical charge, repels it with a force of 8.9874 × 10⁹ N. This constant allows us to solve Coulomb's Law.

Permittivity and Mathematical Expression

The units are determined by the permittivity

Darwinism and Natural Selection

Darwinism describes the struggle for survival caused by limited resources, resulting in a process of natural selection. The fittest individuals—those with the best characteristics to adapt to their environment—survive, while the least adapted perish. These survivors transmit their advantageous traits to their offspring.

Origin of the Cosmos: The Big Bang

The Big Bang was an initial expansion of the universe from all points of a field. This event did not occur in one specific location; rather, it was an amorphous state subjected to extreme temperatures that expanded simultaneously in all directions. As the universe expanded, space filled with light and matter, causing celestial bodies to separate.

Future Scenarios

Electric Field Flux and Gaussian Surfaces

The flow of an electric field through a Gaussian surface, also known as electric flux (symbol Φ), is a property of any vector field referring to a hypothetical surface that can be closed or open. For an electric field, the flow (Φe) is measured by the number of lines of force crossing the surface.

To define Φe precisely, consider an arbitrary closed surface within an electric field. The surface is divided into elementary squares (ΔS), each of which is small enough so it can be considered flat. These area elements can be represented as vectors ΔS, whose magnitude is the area itself, the direction is normal to the surface, and the orientation is towards the outside. For each elementary square, it is...

Electric Potential

Electric potential represents the potential energy of a unit positive charge located in an electric field. The electrical potential difference between point A and point B equals the work done by the electric field in moving the unit positive charge from A to B: (V_a - V_b = ∫ E · dr). The electric potential at a point in space is the work done by the electric field to move a unit positive charge from that point to infinity. Its SI unit is the Volt.

If a positive charge q is moved from A to B, the work done by the electric field is: W = q (V_a - V_b). The electric potential energy of a charge at a point in space is related to the electric potential at that point by: E_p = q · V

Potential Energy of a System of Charges

E_p = K (Q₁...

Understanding Power in Physics

In physics, power is defined as the amount of work done per unit time.

Mechanical Power

Mechanical power is the power transmitted through the action of natural forces or contact with mechanical elements such as levers and gears.

Common Power Units

• Watt (W)
• Horsepower (HP)
• Kilogram-meter per second (kgm/s)
• Erg per second (erg/s)

Free Fall Dynamics

Free fall is the movement of a body under the exclusive action of a gravitational field. From the standpoint of classical physics, a reference system in free fall is accelerated by the force of gravity and, as such, is non-inertial.

Principles of Free Fall

In free fall, aerodynamic resistance is neglected, analyzing the motion as if it occurred in a vacuum. When a body starts from...

Understanding the Microscope

The microscope is an optical instrument used to enlarge images.

Microscope Systems

• Mechanical System: Comprises the structural components that support the instrument.
• Optical System: A set of lenses arranged to magnify images.
• Lighting System: Parts that reflect, transmit, and regulate the light needed for observation.

Mechanical Components

The mechanical parts of the microscope include: the base (foot), the body tube, the arm (handle), the stage (plate), the stage clips, and the coarse and fine adjustment knobs.

Optical and Lighting Functions

• Optical System: Responsible for reproducing and enhancing images through a set of lenses.
• Lighting System: Directs sunlight or artificial light toward the object being observed.
• Light

Understanding Sound: Properties and Behavior

Sound is produced by the vibration of an elastic medium, which can exist in three states (solid, liquid, gas).

An elastic medium possesses the ability to regain its original shape after deformation.

Types of Sound

The sounds audible to the human ear have frequencies between 20 Hz and 20,000 Hz.

• Infrasound: Sounds below 20 Hz.
• Ultrasound: Sounds above 20,000 Hz.

Sound is a longitudinal mechanical wave where the medium undergoes vibrating pressure variations. Key aspects include:

• Compression: High-pressure zone.
• Rarefaction: Lower-pressure zone.

Sound Intensity and Volume

The intensity of a sound wave is a physical quantity defined as the sound energy carried by the wave per unit time through a unit area. It...

Fundamental Concepts of Force and Motion

Force: Every action can change the state of rest or motion of a body, or result in any deformation. Newton: The force that, when applied to a body of mass 1 kg, communicates an acceleration of 1 m/s².

Resultant Force: The vector sum of all forces in the system.

Conditions of Equilibrium

• Translational Equilibrium: For translational motion not to exist, the resultant of the system of forces that acts on the body should be null.
• Rotational Equilibrium: For rotational movement not to exist, the resultant moment of the system of forces that acts on the body must be zero.

Universal Gravitation and Electric Fields

Universal Law of Gravitation: Two material particles attract each other with a force proportional to...