[Phy] F.3 有D野唔明(reflection)

因為玻璃不適合吸收光的波長..但是當然會有一些光波被玻璃吸收，令玻璃的能量更多。

而墻就相反了。

Light is electromagnetic waves in nature. The transmission, reflection and absorption of light on an object actually depends very much on the natural frequency of vibration of electrons in the object.
Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural frequencies of vibration of the electrons in objects. When light waves of these frequencies strike an object, the electrons in the atoms of the object begin vibrating. But instead of vibrating in resonance at a large amplitude, the electrons vibrate for brief periods of time with small amplitudes of vibration; then the energy is reemitted as a light wave. If the vibrations of the electrons are passed on to neighboring atoms through the bulk of the material and reemitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted, and the object appears transparent. Glass is one such material.
If the vibrations of the electrons are not passed from atom to atom through the bulk of the material. Rather the electrons of atoms on the material's surface vibrate for short periods of time and then reemit the energy as a reflected light wave. Such frequencies of light are said to be reflected. The object then appears as opaque.
The following web-page is informative, try to have a look on it:
http://www.physicsclassroom.com/Class/light/u12l2c.cfm