Movimiento de carga en el campo magnético

cigemexico

14 Dec 201109:23

Mindmap

Keywords

💡Magnetic Field

A magnetic field is a vector field that exerts a force on moving electric charges, electric currents, and magnetic materials. In the video, the magnetic field plays a crucial role in trapping charged particles in the Earth's atmosphere, preventing them from escaping into space, and is essential for the formation of the ionosphere. The script explains how charged particles interact with the magnetic field, resulting in circular or helical motion.

💡Ionosphere

The ionosphere is a region of the Earth's upper atmosphere, extending from about 60 to 1000 kilometers above the Earth's surface, where the air is ionized by solar and cosmic radiation. It is composed of charged particles and is vital for long-distance radio communication. The video discusses how the ionosphere is formed and its importance in trapping charged particles due to the Earth's magnetic field.

💡Charged Particles

Charged particles are particles that have an electric charge, either positive or negative. In the context of the video, these particles are created by the ionization of air molecules in the ionosphere and are influenced by the Earth's magnetic field. The script explains how these particles are trapped and move within the magnetic field, contributing to the ionosphere's formation.

💡Lorentz Force

The Lorentz force is the force experienced by a moving electric charge in a magnetic field. It is given by the equation \( \vec{F} = q(\vec{v} \times \vec{B}) \), where \( q \) is the charge, \( \vec{v} \) is the velocity of the charge, and \( \vec{B} \) is the magnetic field. The video uses this concept to explain how charged particles are influenced by the magnetic field, leading to their circular or helical motion.

💡Right-Hand Rule

The right-hand rule is a common mnemonic for understanding the direction of the Lorentz force and other vector cross products in physics. The video script describes using the right-hand rule to determine the direction of the magnetic force acting on a positively charged particle moving in a magnetic field, which is crucial for visualizing the particle's trajectory.

💡Centripetal Force

Centripetal force is the force that keeps an object moving in a circular path. In the video, it is mentioned that the magnetic force acting on a charged particle is a centripetal force that keeps the particle in a circular orbit within the magnetic field. The script provides the formula \( F = \frac{mv^2}{r} \), where \( F \) is the centripetal force, \( m \) is the mass of the particle, \( v \) is its velocity, and \( r \) is the radius of the orbit.

💡Cathode Ray Tube (CRT)

A cathode ray tube is a type of display technology that uses an electron beam to excite phosphors and produce images on a fluorescent screen. The video script mentions CRTs in the context of demonstrating the effect of a magnetic field on the trajectory of electrons, which is analogous to the behavior of charged particles in the ionosphere.

💡Helical Motion

Helical motion is a type of motion where an object moves in a three-dimensional spiral path. The video explains that when the velocity of a charged particle is not perpendicular to the magnetic field, the particle's motion becomes helical, combining linear and circular components. This concept is illustrated by the script when discussing the behavior of electrons in a CRT.

💡Electron

An electron is a subatomic particle with a negative electric charge. In the video, electrons are discussed as one of the charged particles that are ionized from air molecules in the ionosphere and are affected by the Earth's magnetic field. The script describes how electrons move in a circular path within a magnetic field, contributing to the light emitted in a cathode ray tube.

💡Magnetic Deviation

Magnetic deviation refers to the change in the path of a moving charged particle due to the influence of a magnetic field. The video script describes how placing magnetic bars near a CRT can cause the electron beam to deviate from its straight path, demonstrating the effect of the magnetic field on charged particles.

Highlights

The ionosphere, located above 80 kilometers from the Earth's surface, consists of charged particles and plays a crucial role in long-range radio communication.

Sun's ultraviolet rays ionize air molecules in the ionosphere, creating ions and electrons.

The magnetic force equation is given by the vector \( \vec{F} = q(\vec{v} \times \vec{B}) \), where \( q \) is the charge, \( \vec{v} \) is the velocity vector, and \( \vec{B} \) is the magnetic field vector.

If a charge moves with its velocity vector parallel or antiparallel to the magnetic field, the magnetic force acting on the charge is zero.

For a positively charged particle moving perpendicular to the magnetic field, the magnetic force is maximum, causing the particle to follow a circular path.

The right-hand rule can be used to determine the direction of the magnetic force acting on a positively charged particle.

Magnetic force does not do work on a charge moving in a magnetic field, thus the charge's energy and velocity remain constant.

The magnetic field can trap charged particles, as demonstrated by the circular motion of electrons in a magnetic field.

The centripetal force for circular motion is given by \( F_{\text{centripetal}} = \frac{m v^2}{r} \), where \( m \) is the mass, \( v \) is the velocity, and \( r \) is the radius of the orbit.

The radius of the circular orbit can be calculated using \( r = \frac{m v}{q B} \), where \( q \) is the charge and \( B \) is the magnetic field strength.

The Crookes tube, an experimental device, demonstrates the circular motion of electrons under the influence of a magnetic field.

Increasing the acceleration potential increases the velocity of electrons, resulting in a larger radius of the circular path.

Increasing the current in the Helmholtz coils increases the magnetic field, which in turn decreases the radius of the electron's circular path.

In a cathode-ray tube (CRT), without deflection systems, a point is seen at the center of the screen, but placing magnetic bars with opposite poles facing each other can deflect the electron beam.

The trajectory of electrons in a CRT can be a circular arc or a helix, depending on the angle between the velocity vector and the magnetic field.

The Earth's magnetic field prevents ionized particles from escaping the atmosphere, trapping them and forming the ionosphere.

The distortion of a conventional television image when a magnet is placed nearby can be explained by the influence of the magnetic field on the electron beam.