Thanks for all your emails, this week, for the Planet Pals section of the newsletter. Hay-Wire will try and answer your science questions in future issues of the e-zine, but for this issue we’ve picked this question from Dan (age 11) from Chester:
“I’m hoping for a new CD player for Christmas but I don’t know how CDs work. Can you tell me please?”
Here’s the answer:
Believe it or not, there is no actual sound on a compact disc. When music is recorded, it is turned into a digital code, and all the sounds are changed into special numbers. If you look at the surface of a CD under a microscope you’ll see millions of bumps and grooves, which are how the digital code is engraved onto the CD.
When you play the CD, a small laser in the CD player shines a tiny beam on the surface of the disc. As the disc turns, the beam is reflected off the bumps and grooves, and a light receiver catches the beam and records the way it is bounced around. This re-creates the digital code, which is then changed back into musical notes that you hear.
I hope you get what you ask for, Dan!
