1. Science Pages
Kerri Bond

2. Words to know
Transparent: (of a material or article) allowing light to pass through so objects behind can be distinctly seen. (example: GLASS)
Opaque: not able to be seen through; not transparent.
Oscillate: to move or swing back and forth at regular speed
Resonate: the quality in a sound of being deep, full, and reverberating.
Molecules: group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
Amplitude: the maximum extent of a vibration or oscillation, measured from the position of equillibrium

3. Transparent vs. Opaque Materials pg. 12
Topic Question – (How is it possible for light waves to pass through a glass window, but not a piece of plywood?)
First you’d have to examine the atomic building blocks that make up everything in the world including you and I (which are made up of atoms containing electrons.) Electrons are generally bound to a particular atom, the oscillating electric fields of an incident electromagnetic wave can cause an atom’s outer electrons to vibrate. Many objects have a natural frequency at which they tend to oscillate (or to move back and forth). When objects encounter a periodic disturbance that matches their natural frequency, their amplitude of oscillation increases strongly. This phenomenon is called resonance.
(with the example given, electrons within the molecules of everyday matter have natural frequencies of oscillation; the exact frequency is dependent upon the molecular composition of the material)

4. Opaque
When light of a given frequency is incident upon a material with electrons having the same resonant frequency, the light wave is absorbed. The energy of the incident light wave is then converted into thermal energy of the atom, which collided and interacts with neighboring atoms, thereby raising the temperature of the material. Materials that absorb particular frequencies of light are said to be opaque to those frequencies. Meaning that light can’t pass through an object.

5. Transparent
Topic Question (What happens if incident light doesn’t match the resonant frequency of the material?_
The electrons are still set into vibration, but at lower amplitudes for shorter period of time. The vibrating electrons then generate their own electromagnetic wave that propagate outward and the which causes less energy to be converted into heat. This is what we call transparency. If a material is transparent, the remitted waves will be continuously absorbed and emitted by neighboring atoms until the wave exits from the opposite side of the glass (or object/material).

6. Visible Light & Color (The Visible spectrum)
Topic Question – (Why is it that we see color?)
The colors of light we see depend on frequencies of light that reach our eyes. The lowest- frequency light in the visible spectrum appears to most people as read and the highest- frequency light as violet. Although there are an infinite amount of frequencies within the visible spectrum, conventionally we group them into seven colors which consist of red, orange, yellow, green, blue, indigo, and violet.
Something To Know
Please note that although we often describe light as “blue” or “red” based on its frequency, color is not an inherent property of any electromagnetic wave. Nor is the color of an object on or within the object itself. Color is a physiological experience, involving our eyes and brain, that differs from person to person. For instance, even if the same light waves reached another persons’ eyes, a person with color blindness might perceive those waves differently than a person with normal color vision.

7. Selective Absorption & Reflection
Topic Question (what does it mean for an object to appear red, yellow, or violet?)
Some objects we see, such as the Sun, the stars, campfires, lamps, and lasers, are sources of visible light. We see them because they emit electromagnetic waves in the visible spectrum as the result of electrons being rearranged within atoms and molecules. However, we also see objects that aren’t sources of light, but only because they reflect light from other sources to our eyes.
Take the moon, for examples, the moon doesn’t produce its own light. The lights we see on the moon is reflected form the sun causing us to see the moon at night.
It’s important to note that an object can only reflect frequencies that exist within the light that is incident upon it. In other words, the apparent color of an object is dependent upon what kind of light illuminates it.
Consider an apple that appears red when illuminated by white light. Under red light, the apple will still appear red because red wavelengths are clearly still able to be reflected. However, under green light, the apple with appear black because of how the green wavelengths of light are completely absorbed by the apple, and none are reflected to the observer.

8. Selective Transmission
Don’t worry we’re almost there… Hang tight peeps ;p
Ordinary window glass appears colorless because it transmits all frequencies of visible light equally. It’s also possible for materials to absorb certain frequencies of visible light but allow others to be transmitted. Rubies for example are a verity of the mineral corundum, which consists of aluminum. oxide in a crystalline structure. In its purest form, corundum is colorless. The red color of rubies is due to chromium impurities scattered throughout the crystal structure, which absorb frequencies of light within the visible spectrum except red. Interestingly, sapphires also belong to a corundum family, but instead contain titanium and iron impurities that lent them their stunning blue color.