Work Motivation

Breakthrough Junior Challenge 2019 Video | EMW in life & The principle of EMW

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Hello I’m Beini nowadays we have so many advanced facilities that make our life much easier and convenient the one of the greatest equipments mobile phone is a necessity we can’t leave without the TV show which attracts you every single day leads the battle among you and your sibling for the remote control applications like communication microwave oven remote control all started at one important concept – electromagnetism don’t you ever ask questions like how these terrific applications work and how these applications relate to which certain scientific principles what knowledges we will get in-depth from the principles continuing this video let’s get started for our journey we talked about the mobile phone at the beginning we use it to communicate with others when you call somebody far from you your words turn into a digital signal the antenna in your phone receives the digital signal and transmits it to a form of electromagnetic waves the electromagnetic waves then travels through the way to the receiver tower the tower will play a role in further signal processing and sends the signal to the target tower microwave oven literally what is microwave basically microwave is a high frequency electromagnetic wave it cannot produce heat itself the magnetron in the microwave oven transfers electric energy into microwaves and they penetrate food at an oscillation frequency of 2,450 MHz per second the food then absorbs the microwaves oscillates rapidly at 2.45 billion times and produces a lot of amount of frictional heat finally the food is heated Ms.Lan Ms.Lan what is electromagnetic wave great question EMW is a dynamic state of electromagnetic field or electromagnetic field spreading as waves it was proposed by James Clerk Maxwell in 1865 EMW possesses wave-particle duality you may be confused about this complicated stuff but let’s be simpler hmm what about sound wave most of us know sound wave too well it was consisted of crest trough wavelength frequency and wave speed the structure of EMW is the same as the one of sound waves but what’s different is that EMW doesn’t need medium to propagate and it can propagate at vacuum in addition the EMW propagates in a constant rate of velocity which is three times 10 to the power of 8 meters per second well you know the speed of light oh I see Ms.Lan but could you please tell me what is the expression for the energy of EMW okay the magnitude of the energy of EMW is depends on poynting vector which is S equals E times H poynting vector means that energy flow density vector in electromagnetic field in this expression S represents poynting vector E represents electric field strength H represents magnetic field strength the unit is watts per meter square in conclusion electromagnetic waves are everywhere it can’t be seen or touched but it has had a profound impact on today’s technology and communication thanks for watching