Microondas, regaliz y la velocidad de la luz

Benjamín Montesinos

¿Tienes una barra de regaliz en casa? Si no, baja a la tienda de chuches más cercana, cómprate unas cuantas y disponte a medir la velocidad de la luz usando tu microondas.

Este es un sencillo -y sorprendente experimento- para medir la velocidad de la luz con una barra de regaliz y un microondas:

Paso 1: quítale al microondas la pieza de plástico que está en el eje de giro, para evirtar que el plato de vueltas. Con dos trozos de cello pega la barra de regaliz en el plato y ponla de modo que la barra quede paralela a la puerta.

Paso 2: cierra el microondas, y a baja potencia, por ejemplo a 200 watios, enciéndelo. Quizás tengas que hacer algunas prueba, pero en eso consiste la experimentación. Verás que el regaliz se curva en forma de onda: algunas zonas quedan al nivel del plato y otras se elevan algo así como 3 cm. Apaga el microondas y saca el plato.

Paso 3:  Cuando apagas el microondas la barra de regaliz se enfría y tiene el aspecto que se muestra en la fotografía de arriba: verás que las zonas que se han elevado están quemadas pero hay otras zonas intactas (los dos pequeños «valles» que se aprecian en la foto). Con una regla mide la distancia aproximada entre los centros de esos dos valles. En nuestro caso, es más o menos 6 cm.

Paso 4: dale la vuelta al microondas y mira la frecuencia de las ondas. Viene indicada en la placa con las características técnicas. En el microondas que nosotros usamos es 2450 MHz. «MHz» significa «Megaherzio» (millones de herzios) y los «herzios» son simplemente número de oscilaciones por segundo, de modo que las unidades son la inversa de un tiempo, que se indica como «s-1»

Multiplica por 2 la distancia que mediste antes, y multiplicala por 2.450.000.000 s-1.
El sorprendente resultado es 12 × 2.450.000.000 = 29.400.000.000 cm/s =294.000 km/s… ¡la velocidad de la luz!

¿Es causalidad? ¿Qué está pasando? La explicación es sencilla: el microondas es una cavidad que produce ondas estacionarias. Hay puntos del microondas donde la amplitud de las ondas es cero y otros donde esa amplitud es máxima. En nuestro caso, el hecho de que cada seis centímetros el regaliz no se haya quemado, significa que en esos puntos el calentamiento es nulo, y por tanto la amplitud de las microondas es cero.

La longitud de onda de la radiación es dos veces la distacia entre dos de estos puntos estacionarios (llamados técnicamente «nodos»). El regaliz por tanto nos dice que la longitud de onda en el microondas es de 12 cm.

Una fórmula muy conocida en física dice que la velocidad de la luz es igual al producto de la longitud de onda por la frecuencia. Haciendo la operación que hemos indicado, se ve que la exactitud del experimento es grande. El valor «oficial» de la velocidad de la luz es 299.792,458  km/s.

¡Ánimo y enviadnos vuestros resultados!

ADDENDUM (DByN):
Midiendo la velocidad de la luz: el contexto histórico

Compartir:

1.099 comentarios

  1. That’s really excellent and useful information. I am happy you shared with all this particular advice that is valuable around. Please continue the wonderful work. Thank you for sharing

  2. 2020 is the best place to get fast updates of the most recent Sarkari 2020. For forthcoming enrollment warnings that are accessible on sarkariresult-update,Get Sarkari Naukri latest & upcoming jobs news from Government Jobs Vacancy, Public Sector Jobs, Central Govt,Sarkari Naukri update latest job news for govt sector companies. Central Sarkari Exam 2020 State Vacancies including Railway Jobs, UPSC, SSC, PSC, banking, and so forth. sarkariexam 2020
    sarkari result

  3. inewjob 2020 is the best place to get fast updates of the most recent Sarkari 2020. For senrollment warnings that are accessible on inewjob, Sarkari Naukri, Freshersworld, Sarkari exam, Rojgar Result are for the most part accessible in this site Job ready page and get notified of all Central Sarkari Exam 2020 State Vacancies including Railway Jobs, UPSC, SSC, PSC, banking, and so forth. sarkariexam 2020
    sarkari result

  4. Are you fed up with traditional ways to withdraw your payment or stimulus checks? Learn how to enable cash app direct deposit and get instant payment to. To know more information about Enable Cash App Direct Deposit visit here: Cash App Direct Deposit

  5. Get Sarkari Naukri latest & upcoming jobs news from Government Jobs Vacancy, Public Sector Jobs, Central Govt,Sarkari Naukri update latest job news for govt sector companies
    Sarkari Naukri, Freshersworld, Sarkari exam, Rojgar Result are for the most part accessible in Job ready page and get notified of all Central Sarkari Exam 2020 State Vacancies including Railway Jobs, UPSC, SSC, PSC, banking, and so forth. sarkariexam 2020
    sarkari result

  6. Garmin’s product offerings have extended to completely cover the flying, marine, and car enterprises. Garmin Express is an application that is utilized to regulate and watch the working of the devices on your computer. It can be used for enrolment of a new product, store all the fitness data, synchronization of the remote device data and everything else which is necessary.

  7. This is a really too good post. This article gives truly quality and helpful information. I’m definitely going to look into it. Really very useful topic info is provided here. Thank you so much buddy and Keep up the good work.

  8. Thanks for sharing this blog. It is very useful for us. I really like this post very much. I am curious about some of them. I hope you will give more information on this topic in your next article. This is such a great resource that you are providing and you give it away for free.

  9. Kindle Paperwhite Troubleshooting welcomes troubled kindle users who are unable to fix Kindle technical problems such as screen unresponsive, WIFI inactive, poor battery life, etc. Your Kindle technical problems will be addressed by technical specialists who have vast experience handling such technical problems with Kindle.

  10. In order to access all the features of Bitdefender, you have to create a Bitdefender account. Therefore, follow the below-given guide for account creation and Bitdefender login.

  11. This Blog is very informative for us. Thanks for writing it. In this article, some examples help me in applying in daily life. You have explained each and everything very well in detail. I hope you will write more amazing pieces which help us in our daily routines. Tech Ription

  12. For the very first time, I read your blog and loved it. Your way of delivering content is amazing and appreciable. Hope you will continue this and provide new, unique, and strong content from your side. For me, it’s a five stars article. Technargle

  13. We are providing free Amazon Prime Video Cookies on this website every hour. Basically, tons of websites on the internet also provide Amazon prime cookies but only a few are working and the rest are useless. But here, you will get totally working cookies for your Amazon Prime.

  14. A dispute between users and Cash App over transfers and payments occur for many reasons. From unauthorized charges on debit cards to accidental payment, any kind of problem may arise unexpectedly. But, the good thing is that Cash App users can dispute a payment with ease of mind. Cash App dispute process is all about contacting Cash App customer service.

  15. Sorry to say but the fact of the matter is that you can’t delete Cash App transaction history. Any particular or all past transactions occurred on Cash App couldn’t be edited in any way. There is no such option available in the application or site of Cash App that can let you customize your Cash App payment statement. Only the alternative option is to delete your Cash App account.

  16. . There is no such option available in the application or site of Cash App that can let you customize your Cash App payment statement. Only the alternative option is to delete your Cash App account.

  17. The WBO Heavyweight Championship match will afford the two boxers the opportunity to add to their arrays of honors and achievements. A victory for Fury will help him retain his status as an undefeated boxer and increase his winning records to 31 in 32 fights. Wilder will hope to win in order to restore his lost glory from the loss to Fury in February and to prove that he is still one of the best heavyweight boxers on the planet.
    https://furyvswilder3fight.live/

  18. Buchen Sie günstige Urlaubspakete für romantische Reisen, Familienurlaube oder einen Wochenendausflug. Finden Sie die besten Reiserabatte und Angebote für Ihre nächste Reise bei der vertrauenswürdigen Firma. Si, ich schlage Sie der Firma «günstiger-reisen.de» vor, die die besten Angebote für günstige Reisepakete zu erschwinglichen Preisen bietet.

  19. To experience all of the fantastic features of Garmin, you must download it at the first place. Garmin.com/Express – you will get the Mac or Windows version of Garmin device. You can follow the installation instruction to install Garmin express on your device.

  20. Rent a PC provides Desktops Laptops for a rental basis from a few days, months or even years. Flexible Contracts with Quick Support Laptop on Rent.

  21. Is your video stream getting stopped due to bad internet connections or due to dead network area zones? Boost your surfing experience with mywifiext.net. To get best assistance get in touch with us.

Deja un comentario