Re: pinhole Opaque and Transparent Materials

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From: Paul Doherty (pauld@exploratorium.edu)
Date: Wed Apr 18 2001 - 10:03:24 PDT 

Message-Id: <l03110709b7037853b5b0@[192.174.2.173]>
Date: Wed, 18 Apr 2001 10:03:24 -0700
From: Paul Doherty <pauld@exploratorium.edu>
Subject: Re: pinhole Opaque and Transparent Materials

Hi Jhumki

This answer is based on the 1870 model of light from Maxwell.

The incident light can be viewed as a long series of oscillations.
The electrons oscillate back and forth under the pushes from these
oscillations.
Whenever electrons oscillate back and forth they do emit radiation.

However the oscillating electrons do collide with electrons in neighboring
atoms, disrupting the oscillation and creating heat. This disruption
happens a little even in transparent materials. The greater the disruption
the more light is absorbed by the transparent material.

The electron oscillations lag behind the driving oscillation by just a
fraction of one cycle called a phase lag. Since each atom delays its
re-emission by a fraction of a cycle, the re-emitted light is slowed down
and we have the index of refraction.

Paul D

Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld

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