• Question: How do radios and speakers work?

    Asked by 534bera34 to Colin, John, Kevin, Shikha, Triona on 17 Nov 2014.
    • Photo: Kevin Motherway

      Kevin Motherway answered on 17 Nov 2014:

      Speakers are esentially electric motors and microphone are little generators. Whenever you have a wire in motion in a magnetic field it’ll generate a current: and whenever you have an electrical current traveling in a wire you’l get a magnetic field. So in a microphone you have a little paper cone or diaphragm: you speak and the sound wave of your voice hits the diaphragm and it moves up and down at the same frquency as your voice. At the bottom of the diaphragnm is a little loop of copper wire surrounded by a circular magnet, so when the wire moves it generates a tiny electrical current (the elctrical signal of your voice). The wire transmits the sound to the speaker where you have an electical wire surrounded by a magnet. the mangentic field in the wire pushes against the magnetic field of the magnet and you get movement. Attached to this coil of wire is a much bigger paper cone or diaphragm that moves and causes a pressure wave in the air or….sound as its known. the bigger the cone the lower the frequency so Bass Woofers have big paper cones and big magnets. High frequancy sound have small cones and small magnets (trebble tweeters). If you’re playing a CD or MP3 it simply the encoded instructsions to tell the speakers what frequancy to vibrate at and at what volume…

      Did you know it really matters where you locate your tweeters as your brain is really good at locating high frequcncy sound, but it doesnt matter where in the room you put the Bass Woofer as you brain is really rubbish at locating low frequency sound.

    • Photo: Shikha Sharma

      Shikha Sharma answered on 20 Nov 2014:

      Hi 534bera34,

      First let’s see how does radio works and how we can listen to good music or talk show in our radio set and how we see our favorite movie channel, cartoon channel or sports channel in a television set. Remember, here we transmit audio, video or data through radio frequency.
      First audio or video is recorded in a recording station. A frequency modular then converts the audio into an intermediate frequency. A transmitter then converts intermediate frequency into final radio frequency called broad cast frequency. The final radio frequency or broadcast frequency is basically the unique identity of the particular audio. Final radio frequency is then amplified and sent to a transmitter to spread the signal to large area.

      If you have a radio set, you adjust the tuner to capture particular final radio frequency from air. Then a demodulator converts the radio frequency into audio. The audio signal then boosted to desired volume through an amplifier. And finally audio comes not from a speaker, and we hear the audio file.

      Now let’s see how a speaker works. A typical speaker contains a permanent magnet, a coil which acts as electro-magnet and a cone made of flexible paper or plastic. The cone is kept attached to the coil. When a fluctuating electric current passes through the coil, it becomes an electro-magnet. Its direction of magnetic field changes rapidly. Therefore, it is continuously attracted and repelled by the permanent magnet causing vibration in the coil. The vibration of coil is then amplified by the cone releasing sound wave in the air and we finally here the sound.

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