Science Unit C Flashcards
What did Pythagoras try to explain?
Pythagoras tried to explain how we see light. He thought light consisted of beams. These beams came from a person’s eyes in straight lines, and the sense of sight occurred when these beams touched the objects a person was looking at.
Was this theory true?
There was a problem with this theory. If it were true, then we would be able to see in the dark. In spite of this problem, Pythagoras’s theory was accepted for many years.
What did Euclid try to explain?
Euclid discovered that when you shine a beam of light onto a flat mirror, the angle between the incoming beam and the mirror is equal to the angle between the reflected beam and the mirror. He also suggested that light travels in straight lines.
What did Ptolemy describe?
The astronomer Ptolemy described how light beams bend when they go from air to glass
What did Al-haytham do?
In about A.D. 1000, a great Arab scientist called Al-Haytham took up the study of light. He studied the work of Euclid and Pythagoras and wrote a book on optics
What did Al-haytham show?
He showed that light bounces off objects and then travels to the eye, showing that light does not come from the eyes but rather light travels to the eyes
What happened to Pythagoras´s theory?
Because Al-Haytham’s explanation was so detailed, Pythagoras’s theory was abandoned.
What was Sir Isaac Newton fascinated by?
Sir Isaac Newton also was fascinated by light, and he was especially interested in the colors of a rainbow.
What was Sir Isaac Newton fascinated by?
Sir Isaac Newton also was fascinated by light, and he was especially interested in the colors of a rainbow.
What was Sir Isaac Newton fascinated by?
Sir Isaac Newton also was fascinated by light, and he was especially interested in the colors of a rainbow.
What did Newton show?
By shining a light through a prism, Newton showed that white light is actually a mixture of different colors of light. As the light passed through the prism, it split up into many separate colors. Passing the rainbow colors through a second prism, Newton showed that the separate colors combined back into white light.
When did Ole Romer show his measurment?
The first reasonably accurate measurement was made by Ole Romer in 1676.
Who refined his measurement and when?
His measurement was refined in the 1920s by a scientist named Albert A. Michelson.
What did Ole Romer show?
He placed two mirrors on the tops of two mountains in California and measured the distance between the two mirrors, which was 35.4 km. He then sent a beam of light from one mirror to the other. He used extremely accurate timing devices to measure how long it took the beam to reach the second mountain
What is the earths atmosphere?
The speed of light as it travels through Earth’s atmosphere to be 299 798 km/s.
What are the properties of light?
- Light travels in straight lines.
- Light can be reflected.
- Light can bend.
- Light is a form of energy
Optical device
Is any technology that uses light.
Microscope
Allow you to see great detail by combining the power of at least two lenses
What is a refracting telescope?
Refracting telescopes have two lenses, one on each end of a long tube. The larger lens is the objective lens that gathers light and focuses the rays toward the eyepiece, which in turn allows you to see the object larger than it appears with the unaided eye.
What is a reflecting telescope?
Reflecting telescopes use a large circular mirror that curves inward. This curved surface gathers light extremely well. Another mirror inside the telescope directs light to the eyepiece, which leads to your eye.
What are Binoculars?
They are simply two short refracting telescopes fixed together. Binoculars are not as powerful as telescopes but they are much more convenient.
Ray Diagrams
Scientists use ray diagrams to show how light travels. The light travelling from a source is shown as straight lines called rays. Each ray ends with an arrow to indicate the direction of travel.
How are shadows made?
Ray diagrams also help explain shadows. If light hits an object, it can’t go any farther. So if an object gets between the light and our eyes, we perceive this lack of light as a shadow
Transparent
Transparent materials, such as glass or clear plastic, can transmit light, meaning
light travels straight through them. That’s why you can see clearly through a window pane.
Translucent
Translucent materials allow some, but not all, light to pass through. A frosted window pane is a good example of a translucent material. Some light can pass through, but you can’t see what’s on the other side of the frosted glass in any detail.
Opaque
Opaque materials do not allow any light to pass through them. They absorb or reflect the light that hits them. Since light cannot get through an opaque object, a shadow is created behind it. Wood, metal, and brick are examples of opaque objects.
Non-luminous
Pencils and other opaque objects are non-luminous, meaning they don’t produce light
Luminous
A light source is luminous; it produces light. Light from a light source (the sun, a lamp) bounces or reflects off the pencil and hits your eyes.
Regular reflection
Regular reflection occurs when light rays hit a smooth surface. The incoming rays travel parallel to one another. When these rays strike a smooth surface, they all bounce off in the same direction, and so the reflected rays stay parallel to one another
Diffused reflection
When light rays strike a rough or uneven surface, diffuse reflection occurs. When the light rays hit the surface, they reflect, but due to the rough surface, each of the rays is reflected at a different angle.
Incident Ray
Incident (incoming) rays bounce off as a parallel beam, giving a regular reflection. The shinier and smoother the surface, the better the reflection.
Plane Mirrors
Plane mirrors (flat mirrors) provide the clearest reflections. Using plane mirrors, you can investigate how reflected light behaves.