Name: electromagnetic wave reflection at conductors
Uploaded: 2023-09-18T17:11:17.000Z
Duration: 1 min 15 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Physical Science

PS.7

PS.7.a

Standing Electromagnetic Waves

Recordemos las olas estacionarias formadas en una cuerda apretada. 
Las ondas estacionarias son la combinación de dos ondas que se mueven en la dirección opuesta pero tienen la misma amplitud y frecuencia.
Considere una lámina conductora perfecta colocada en el plano y-z. Una onda electromagnética polarizada linealmente golpea la lámina, mientras viaja en la dirección x negativa.
La onda incidente induce la corriente en la superficie del conductor, lo que resulta en campos eléctricos adicionales, produciendo una onda reflejada con la misma frecuencia y amplitud que la onda incidente.
La superposición de estas dos ondas genera la onda estacionaria. Simplificando estas expresiones, se obtienen los puntos de la onda donde las magnitudes del campo eléctrico y del campo magnético son cero. Estos se denominan nodos o planos nodales.
Un antinodo es un punto en el que la amplitud va desde el máximo desplazamiento positivo hasta el máximo negativo.
Los nodos del campo eléctrico coinciden con los antinodos de los campos magnéticos, y viceversa. Por lo tanto, están desfasados 90 grados en cada punto.

<ol>
	<li>Young, H.D. y Freedman, R.A. (2012). Física Universitaria con Física Moderna. San Francisco, CA: Pearson. Sección 32.5; páginas 1069-1070.</li>
</ol>

ondas electromagnéticas estacionarias

Las ondas electromagnéticas pueden ser reflejadas; la superficie de un conductor o un dieléctrico puede actuar como un reflector. Como los campos eléctricos y magnéticos obedecen al principio de superposición, también lo hacen las ondas electromagnéticas. La superposición de una onda incidente y una onda electromagnética reflejada produce una onda estacionaria análoga a las ondas estacionarias creadas en una cuerda estirada.

Supongamos que se coloca una lámina de un conductor perfecto en el plano yz, y una onda electromagnética linealmente polarizada que viaja en la dirección negativa de x la golpea. Dado que el campo eléctrico no puede tener una componente paralela a la superficie de un conductor perfecto, el campo eléctrico debe ser cero en todas partes en el plano yz. El campo eléctrico de la onda electromagnética incidente no es cero en todo momento en el plano yz, pero esta onda incidente induce corrientes oscilantes en la superficie del conductor, dando lugar a un campo eléctrico adicional. El campo eléctrico neto, que es la suma vectorial de este campo y el campo incidente, es cero en todas partes dentro y en la superficie del conductor. Las corrientes inducidas en la superficie del conductor también producen una onda reflejada que viaja hacia afuera del plano. El principio de superposición establece que el campo total en cualquier punto es la suma vectorial de los campos eléctricos de las ondas incidentes y reflejadas, de manera similar al campo magnético. La superposición de las ondas incidentes y reflejadas genera ondas estacionarias.

<img alt="Equation1" src="/files/ftp_upload/13829/13829_Equation_1.png" style="text-align: center; height: 24px;"> <img alt="Equation2" src="/files/ftp_upload/13829/13829_Equation_2.png" style="text-align: center; height: 22px;"> Simplificar estas expresiones proporciona los puntos en la onda donde las magnitudes del campo eléctrico y magnético son cero. Estos se llaman nodos o planos nodales. A medio camino entre dos planos nodales adyacentes se encuentran los planos de amplitud máxima; estos son los planos antinodales. El campo eléctrico total es una función seno y el campo magnético total es una función coseno. Por lo tanto, las variaciones sinusoidales de los dos campos están desfasadas en cada punto. Los nodos del campo eléctrico coinciden con los antinodos de los campos magnéticos y viceversa. Por lo tanto, están desfasados 90 grados en cada punto. Esto contrasta con una onda que viaja en una dirección, para la cual las variaciones sinusoidales de los campos eléctrico y magnético están en fase en cualquier punto particular.

Ondas electromagnéticas estacionarias

Las ondas electromagnéticas pueden ser reflejadas; La superficie de un conductor o un dieléctrico puede actuar como un reflector. Como los campos eléctricos y magnéticos obedecen a la ...

Education

Educación

JoVE Core

Physics

Física

Unit 1

Unidad 1

Electromagnetic Waves

Ondas electromagnéticas

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

electromagnetic wave reflection at conductors

Electromagnetic waves can reflect from a conductor or a dielectric. When the reflected wave combines with the incoming wave, the result is a standing electromagnetic wave. This is similar to the standing waves formed on a stretched string.

To see how this happens, consider a perfect conductor placed in the yz-plane. A linearly polarized electromagnetic wave moving in the negative x-direction strikes the surface. The electric field cannot have a component parallel to the surface of a perfect conductor, so the electric field must be zero everywhere in the yz-plane.

The incident wave is not zero at the surface, but it induces oscillating currents on the conductor. These currents create an additional electric field. The net electric field is the vector sum of the incident and induced fields, and it is zero everywhere inside and on the conductor's surface. The same surface currents also produce a reflected wave that moves away from the plane.

The total field at any point is the vector sum of the incident and reflected electric fields, and the same idea applies to the magnetic field. This superposition creates standing waves. The places where the electric or magnetic field magnitude is zero are called nodes, or nodal planes. The planes halfway between adjacent nodes have maximum amplitude and are called antinodal planes.

For these standing waves, the total electric field follows a sine function, while the total magnetic field follows a cosine function. The two fields are therefore 90° out of phase at each point. Electric field nodes line up with magnetic field antinodes, and magnetic field nodes line up with electric field antinodes. This is different from a wave traveling in one direction, where the electric and magnetic fields are in phase at a given point.

Electromagnetic Wave Reflection at Conductors

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Explore how reflected electromagnetic waves form standing patterns at conductors, with nodes, antinodes, and electric and magnetic fields out of phase.

Electromagnetic Wave Reflection at Conductors | JoVE K12

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Minnesota Academic Standards in Science

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SC.912.P.10.17

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PS.7.b

Electromagnetic Wave Reflection at Conductors

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