Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Transparency - A Trick of Light?

Learn more physics!

Most recent answer: 10/22/2007
Q:
Why is light able to go through glass but not for example wood?
hillcrest abortion clinic stories of abortion live abortion video
the best android phone link phone tracking apps
married woman looking to cheat married men that cheat most women cheat
types of abortions read what happens when you get an abortion
rite aid prescription transfer coupon open coupon rite aid
levitra pill mostefaiamine.com tadalafil pill
finasteride lasix 40mg cialis 80mg
free viagra samples coupon gallaghermalpractice.com viagra 2016 coupon
pfizer coupons for viagra viagra coupon viagra discounts coupons
acheter viagra pas acheter viagra pas acheter viagra pas
viagra bestellen online viagra pillen kruidvat pillen kopen
viagra bestellen online viagra online shop pillen kopen
claritinekombo warpedfish.co.uk claritine za psa
claritinekombo warpedfish.co.uk claritine za psa
voltaren ára go voltaren
augmentin générique read augmentin sirop
arcoxia 30 arcoxia 90 arcoxia wiki
champix alkohol go champix
champix alkohol mdwguide.com champix
fusidinezuur kopen fusidinezuur kopen fusidic acid
diflucan 150 diflucan djelovanje diflucan sirup
diflucan 150 site diflucan sirup
cialis cialis cialis walgreen coupon
voltaren retard voltaren pomada voltaren spray
singulair 4 mg granulat scottdangelo.com singulair patient information
prescriptions coupons cialis coupon drug prescription card

- nick (age 16)
sixth form college, uk
A:
Nick -

In order to go through a material evenly, light has to avoid two things:

1. being absorbed

2. being scattered off into another direction.

Whether light gets absorbed depends on largely on something that you wouldn't guess from classical physics, but is connected with quantum effects. The energy from light waves gets transferred to other things in packets ("quanta") whose size depends on the frequency of the light. The electrons in different materials have different possible states with specific values of their energies. In order for the light to get absorbed, the energy of one packet has to match up with the energy needed to boost some electrons from one state to another. It happens that in ordinary glass there are very few states with energy differences matching up with the energy quanta for visible light. Wood has lots of different compounds in it, so not surprisingly it has lots of different possible energy differences for its states, so it absorbs a wide range of frequencies.

Whether the light gets scattered depends mainly on how smooth the material is. In a material with very even composition (specifically, a very uniform index of refraction), the light waves travel straight, like waves in a shallow puddle with an even bottom. In materials whose composition varies from spot to spot, the waves scatter in different directions, like water waves in a puddle with a lumpy bottom. Wood is made of cells, with different contents in the cell walls and the cell insides. That unevenness scatters light.

You can find ordinary glass with many little bubbles in it. That sort of glass won't absorb light, but it will scatter it. I believe that the frosted glass of light bulbs just uses an uneven surface to scatter the light. Of course you can also find glass with absorbing sites in it, such as the stained glass used for decorative windows.

If you take a thin sheet of ground up wood (namely paper) it can be too thin to absorb much light yet still too scattering to see through. Usually, if a spot is soaked with oil or water, it fills in some air gaps, making the material more uniform and easier to see through.

Here's a story I hope you enjoy. A young German student, James Franck, was staring at a transparent grease spot in his Greek book, wondering if there was a connection between why he could see through it and why he could see through glass with a smooth surface but not with a rough surface. Unfortunately, he had no idea what to say when his Greek teacher asked him a question. Many years later, after Franck had conducted some of the early experiments establishing quantum mechanics, he got a letter mixed in with ones congratulating him on his Nobel Prize. It asked "Is it possible that you are the same James Franck who was so stupid in my Greek class?"


Mike W.
cheater read wifes who cheat
cheater read wifes who cheat
types of abortions the weeks of pregnancy what happens when you get an abortion
free prescription cards go walgreens prints coupon codes
discount card prescription go print cvs
diprolene kamagra furosemide 40mg
online discount pharmacy dotnetblogengine.net coupon for prescription
prescription drugs discount cards link coupons for viagra printable
coupons prescriptions blog.brunothalmann.com manufacturer coupons for prescription drugs
can i take escitalopram in the morning link can i take escitalopram in the morning
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
cialis coupon card read cialis coupons from manufacturer
naproxennatrium site naproxen migraine
naprosyn roche rileytech.net naprosyn nedir
niacine movidafm.net niacin v hrani
flibanserin online click flibanserin buy
flibanserin online click flibanserin buy
proscar vs propecia for hair loss proscar proscar pris
fluvoxamine (luvox) open fluvoxamina bula
lasix injetavel lasix para emagrecer lasix
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
how expensive is an abortion do abortions hurt abortion clinics dallas tx
how expensive is an abortion do abortions hurt abortion clinics dallas tx

(published on 10/22/2007)

Follow-up on this answer.