What makes petrol rainbows?

  • 6 Replies
  • 8393 Views

0 Members and 1 Guest are viewing this topic.

*

Offline Make it Lady

  • Neilep Level Member
  • ******
  • 4050
  • Hands-on fun for everyone!
    • View Profile
What makes petrol rainbows?
« on: 10/04/2009 19:12:35 »
I love it when it rains on petrol/gas station forecourts. I like the rainbows the petrol makes. But why does it happen? What makes the rainbow in petrol?
Give a man a fire and he is warm for a day, set a man on fire and he is warm for the rest of his life.

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
What makes petrol rainbows?
« Reply #1 on: 10/04/2009 19:42:10 »

*

Offline Make it Lady

  • Neilep Level Member
  • ******
  • 4050
  • Hands-on fun for everyone!
    • View Profile
What makes petrol rainbows?
« Reply #2 on: 10/04/2009 21:09:20 »
Oh, what a hackneyed question. I'm sorry for being so predictable.
Give a man a fire and he is warm for a day, set a man on fire and he is warm for the rest of his life.

*

Offline RD

  • Neilep Level Member
  • ******
  • 8169
    • View Profile
What makes petrol rainbows?
« Reply #3 on: 10/04/2009 21:53:17 »
I love it when it rains on petrol/gas station forecourts. I like the rainbows the petrol makes.

I believe they are referred to as "dead rainbows", (because they are lying on the ground).  [:)]

*

paul.fr

  • Guest
What makes petrol rainbows?
« Reply #4 on: 10/04/2009 22:44:00 »
This, just like the author, is an oldie...

http://www.thenakedscientists.com/HTML/content/questions/question/1708/

    

Why does petrol and oil make a rainbow effect on water ? James, Email, Cambridge

   

This is because the oil spreads out to form a very thin film on the surface of the water, but of varying thickness. In some places it is literally a molecule thick, whilst in other places it is much thicker. When light passes through the oil some of it is reflected back off the different layers of oil, whilst some carries on and is reflected off the surface of the water lying below. Because the light waves have now travelled different distances before being reflected they mix together producing a spectrum of colours - because the thickness of the oil layer varies. For the super intelligent the light spectrum occurs because, having travelled slightly different distances, some of the waves are now 'out of phase' and cancel each other out, producing dark spots, whilst others add together, producing lighter spots.

*

Offline lightarrow

  • Neilep Level Member
  • ******
  • 4586
    • View Profile
What makes petrol rainbows?
« Reply #5 on: 11/04/2009 09:17:05 »
Oh, what a hackneyed question. I'm sorry for being so predictable.
Don't worry, it's not hackneyed, but for whom that already know it. [:)]

*

Offline Madidus_Scientia

  • Neilep Level Member
  • ******
  • 1451
    • View Profile
What makes petrol rainbows?
« Reply #6 on: 11/04/2009 10:11:37 »
Well i've learnt something, the word "hackneyed"