https://padlet.com/cassandra223755/ah8k136u65paz98c en-us 2023-03-10 19:01:50 UTC 2023-03-24 13:33:50 UTC hello@padlet.com cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512242519 2023-03-10 19:09:39 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512242519 cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512242856 2023-03-10 19:10:01 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512242856 cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243176 2023-03-10 19:10:21 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243176 cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243415 2023-03-10 19:10:35 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243415 cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243561 2023-03-10 19:10:46 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243561 cassandra223755 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243679 2023-03-10 19:10:54 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2512243679 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521255795 Francisco Grimaldi - Shown light through a small slit in a dark room and saw color fringes on the wall. This experiment actually showed light diffracting. De Magnete and Galileo’s writings are commonly regarded as the first great works of experimental science. Gilbert’s experiments asked Nature questions and Nature gave him honest answers. Gilbert discovered that if an unmagnetized iron wire is heated until red hot, then cooled while pointing north, it will become magnetic. Today we call this effect thermoremanent magnetization. The effect was actually known in China in the eleventh century. It is an interesting effect, because ancient rocks cooling in Earth’s magnetic field became magnetized in this way, allowing geophysicists to deduce that Earth’s magnetic field flips between north and south every few hundred thousand years. If you had been around 800,000 years ago a compass would have pointed towards Antarctica rather than the Arctic. Gilbert tells us the planets have souls and that our own planet’s soul is magnetic.
Lauren Cooley]]> 2023-03-17 18:29:32 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521255795 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521256714 Johannes Kepler was able to explain how the eye focuses on light and specifies the laws of rectilinear propagation of light. Kepler wrote that every point on a luminous body in the field of vision emits rays of light in all directions but that the only rays that can enter the eye are those that impinge on the pupil, which functions as a diaphragm. He also reversed the traditional visual cone. Kepler offered a punctiform analysis, stating that the rays emanating from a single luminous point form a cone the circular base of which is in the pupil. All the rays are then refracted within the normal eye to meet again at a single point on the retina. For the first time the retina, or the sensitive receptor of the eye, was regarded as the place where “pencils of light” compose upside-down images. If the eye is not normal, the second short interior cone comes to a point not on the retina but in front of it or behind it, causing blurred vision. Johannes Kepler specifies the laws of the rectilinear propagation of light,  Johannes Kepler dedicated much of his work to discover a law for the refraction of light. Unfortunately, he formulated an incorrect law. Nevertheless, it was useful for anticipating the behavior of light in some specific conditions. Some believe that Kepler did not have the elements to formulate the law that was later accepted by the scientific community, that is, the Snell–Descartes law.
Lauren Cooley]]> 2023-03-17 18:30:29 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521256714 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521257701 First telescopes appear in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not receive his patent, news of the invention soon spread across Europe. The design of these early refracting telescopes consisted of a convex objective lens and a concave eyepiece. Galileo improved on this design the following year and applied it to astronomy.   A refractor uses lenses within a tube to refract (bend) light. It's the type of long telescope which you might imagine old-time astronomers, like Galileo, using. Reflectors, on the other hand, use mirrors instead of lenses to reflect light.  A classical Newtonian reflector also has a long tube. But instead of an objective lens, it has an objective or primary mirror. Remember, an objective lens is at the end of the tube where the light comes in. In contrast, the mirror is at the opposite end of the tube.
The objective mirror is not a flat mirror. Instead, it’s a curved (concave) mirror. Reflectors have a second mirror called the secondary mirror. The secondary mirror is a flat plane mirror.This mirror is at the opposite end from the primary mirror. It  is at a 45 degree angle to the direction of the light reflected by the primary mirror. In this type of reflector, the eyepiece is on the side of the tube (not the end).
In a refractor, light enters the telescope near the objective lens. The objective lens is a convex lens. This lens converges the light. The rays of light converge at the focal point. At this point they again begin to diverge. A second convex lens in the eyepiece takes the converging light and straightens it back out. This magnifies the image at the focal point and brings it into focus. Because of this, a refractor has to have a long, clear path to allow the light rays to bend. One of the downsides of this type of telescope is that the image appears upside down.

Lauren Cooley

]]> 2023-03-17 18:31:31 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521257701 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521258168 Marko Dominis discusses the rainbow in De Radiis Visus et Lucis, In the former, inspired by Galileo's presentation of the spy glass in Venice in 1609, Dominis firstly discusses lenses, trying to give a theoretical explanation of the spectacle and spy glass function. Keeping the focus on optics, the second part of his treatise analyzes the appearance of a rainbow.
Lauren Cooley]]> 2023-03-17 18:32:01 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521258168 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521258513 Francesco Grimaldi was a Jesuit mathematician shown light through a small slit in a dark room and saw color fringes on the wall. This experiment actually showed light diffracting. Diffraction effects are when light passing an obstacle is seen to penetrate the geometrical shadow.]]> 2023-03-17 18:32:18 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521258513 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521259311 Johannes Kepler discovers total internal reflection, a small-angle refraction law, and thing lens optics. 
Lauren Cooley]]> 2023-03-17 18:33:00 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521259311 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521262060 Although the idea of magnifying objects with two glass lenses positioned one in front of the other originated as early as the beginning of the 16th century, it was some time before such an instrument was built. The Dutch spectacle maker Hans Janssen and his son Zacharias are generally credited with creating these compound microscopes. The two of them built what was probably the first compound microscope in the last decade of the 16th century. It had a magnification that could be adjusted between 3 and 9x.
Lauren Cooley]]> 2023-03-17 18:36:17 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521262060 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521263560 In 1665 Hooke published his Micrographia, which was primarily a review of a series of observations that he had made while following the development and improvement of the microscope. The great significance of their work was that it revealed, for the first time, a world in which living organisms display an almost incredible complexity. This was the first English book to show observations made under a microscope. ]]> 2023-03-17 18:38:06 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521263560 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521263896 An empirical advance was made by the Dutch astronomer Willebrord Snell with his discovery of the mathematical relation (Snell’s law) between the angles of incidence and transmission for a light ray refracting through an interface between two media. Snell’s law, in optics, a relationship between the path taken by a ray of light in crossing the boundary or surface of separation between two contacting substances and the refractive index of each. The reason light is refracted in going from one medium to another. The higher the refractive index the slower the light travels, which causes a correspondingly increased change in the direction of the light within the material. What this means for lenses is that a higher refractive index material can bend the light more and allow the profile of the lens to be lower. 
Lauren Cooley]]> 2023-03-17 18:38:26 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521263896 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521265668 In La Dioptrique, French philosopher-mathematician René Descartes described light as a pressure wave transmitted at infinite speed through a pervasive elastic medium. In one of his experiments, he produced a rainbow by using a water-filled glass sphere and sunlight. He explained that refraction of light caused the formation of rainbows. He then studied the refraction and emergence of colors of light in a prism. He observed that the different colors of light refracted at varying degrees. He noted that the red light refracted more than the blue light. Descartes explained the emergence of the colors of light using the concept of the plenum, the invisible substance that permeated the universe. He thought that light was a disturbance that traveled through the plenum. He pictured the particles of plenum as tiny balls which were in contact and rotating at the same speed. He explained that when these particles passed through the prism and encountered a slit on the edge, their rotational speed would change. This change resulted in the emergence of color. Other parts of the slit produced other colors of light.
Lauren Cooley]]> 2023-03-17 18:40:34 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521265668 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521266438 Proposed by Robert Hook in 1655, and later improved by Christian Huygens. The Wave theory stated that light was made of waves and each color was a different wavelength. Huygens’ theory states that each point in a source of light sends a wavefront in all directions in a continuous and homogeneous medium called Aether.
Lauren Cooley]]> 2023-03-17 18:41:32 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521266438 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521267718 The French mathematician Pierre de Fermat presented an intriguing derivation of Snell’s law based on his principle of least time, which asserted that light follows the path of minimum time in traveling from one point to another. 
Lauren Cooley]]> 2023-03-17 18:43:09 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521267718 carlee223016 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521268654 Newton held a prism up to a beam of light and saw the separation of colors it made. He wrote a paper about these observations and experiments, which initially established his reputation. In it, he claimed to refute Cartesian ideas of light modification by definitively demonstrating that the refrangibility of a ray is linked to its colour, hence arguing that colour is an intrinsic property of light and does not arise from passing through a medium.]]> 2023-03-17 18:44:16 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521268654 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521273590 In a reflector, light enters the telescope at the end opposite the primary mirror. The mirror is a concave mirror. Similar to a convex lens, a concave mirror converges the light at the secondary mirror. The rays of light converge at the focal point. At this point they again begin to diverge. The convex lens in the eyepiece takes the converging light and straightens it back out. As with the refractor, the image is still upside down. It appears as a virtual image beyond the telescope in the direction the person is looking. 
Lauren Cooley]]> 2023-03-17 18:50:33 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521273590 carlee223016 https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521275028 Ignace-Gaston Pardies was an early opponent of Newton's theory of refraction. His letters with Newton are yound in the Philosophical Transactons of the Royal Society for 1672 and 1673. ]]> 2023-03-17 18:52:26 UTC https://padlet.com/cassandra223755/ah8k136u65paz98c/wish/2521275028