Polarization
Introduction:
PART ONE: POLARIZATION
Method 1:
Two polarized disks were put into a grooved holder with their polarization axes lined up, and a bright red light emitting diode (LED) was placed on one side, and a light sensor was placed on the other side. Light intensity was measured as a function of the plastic rotating polarizer angle from 0 to 180 degrees. Science Workshop was used to measure the intensity for every 5-degree rotation (Fig 1).
Method 2:
The mineral calcite exhibits birefringence (double refraction), and therefore has two different values for its index of refraction. A calcite crystal was placed on top of print and rotated in order to see the difference between the two rays, the ordinary ray and the extraordinary ray. A polarizer was then used to look at the images formed by the calcite.
Method 3:
In order to determine the stress points in a plastic object, we used a photoelastic effect where we looked at the object through a polarizer. When the plastic was squeezed together, changes in the color occurred, displaying points with greater stress.
Method 4:
Polarization by reflection from a non-metallic surface was used in this method in order to help distinguish the plane of incidence, and Brewster's angle. A cardboard disk with a picture on it and a polarizer were placed in the holder, with a piece of black plastic (n=1.491) in between them. Brewster's angle was determined from tan = n, and =56. We then looked through the polarizer at this angle and were able to determine the polarization direction. We also viewed the reflection of a ceiling light directly above the black plastic in order to determine if it was polarized in this case.
Method 5:
In order to determine polarization by scattering, a jar was filled with water and dried milk, and then a flashlight was shined directly down into the top of the jar. From the side of the jar, we looked through a polarizer at the scattered light. From this we determined if the light was horizontally polarized.
PART TWO: LIGHT MEASUREMENTS
Method 1:
A halogen bulb light source was set up at the end of a yardstick, and a light sensor was set up on the yardstick beginning at 0.1m from the light source. Science Workshop was again used to measure the intensity of light ranging from 0.1m to 1.00m (Fig.
Fluorescence measurement provides very important information about the photochemistry of a particular molecule. The first part of this experiment was dealing with the fluorescence behavior of a Leucophor PAF. Information from both spectrophotometry and fluorimetry was used to measure the quantum yield as well as to explain why Leucophor PAF was use as commercial optical brightener. The second part of this experiment dealing with fluorescence quenching of quinine bisulphate solution (QBS) is the presence of sodium chloride.
A spectrum is a group of light wavelengths that are ordered in relation to their wavelength length. The electromagnetic spectrum consists radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. (1)Specifically, this lab looks at the visible light part of the spectrum because one of the colors in the visible light spectrum is shine through the sample. The visible light spectrum consists of colors of red, orange, yellow, green, blue, indigo, and violet. The color chosen to be shine through the sample is affected by the color of sample when mixed with the indicator Ammonium Vanadomolybdate (AMV). The color on the color wheel that is opposite of the solution’s color is the color that is shined through the
We had to do measure the wave angle because it would show us in which
To conduct the experiment, sample solutions will be placed next to a light source, which would be a white LED, with a diffraction grating, which will split and diffract light beams in different directions, between the samples and the detector, the cell phone camera, which will be used to collect images that will then be analysed using a computer software program that measures the amount of light that will be transmitted through the sample. The same samples will then be tested in a commercial spectrophotometer to see how much accuracy there would be using a cell-phone spectrophotometer.
A dipole moment is the degree of separation between two opposite charges. The dipole moment can be either stretched or bent within the compound. As well, stronger bonds in the substance and light atoms will vibrate or rotate at a higher frequency, thus acquiring a higher wavenumber. A wavenumber is the number of wave cycles in one centimetre. The information gathered from the IR spectroscopy can be interpreted from an IR spectrum graph of the material. On such a graph, the wavenumber is on the x-axis, whereas the transmittance percentage is on the y-axis. The transmittance percentage indicates the strength of the light that was absorbed by the substance at each frequency. In addition, the graph is divided into two areas: the function group and the fingerprint region. The function group region on the graph is between 4000 cm-1 to 1000 cm-1, whereas the region less than 1000 cm-1 is regarded as the fingerprint region. The fingerprint region is composed of a series of difficult absorptions.
"Ultraviolet/Visible Spectroscopy (UV-Vis)." YouTube. Royal Society of Chemistry, 28 Sept. 2008. Web. 26 Jan. 2014. .
To understand this week’s experiment one must first understand what a spectroscope is and what it does. With this understanding in hand, one would gain a deeper appreciation for this lab and its intended lesson. “A spectroscope is a device that measures the spectrum of light” (Ball, 2014). More specifically a spectroscope is an instrument designed to split light from different sources into wavelengths. Humans are able to see these wavelengths as different colors. Noting the difference in colors between various light sources, those studying a given light source can identify elements of the light source.
3) Stokes shift - Generally the emitted fluorescent light has a longer wavelength and lower energy than the absorbed light. This phenomenon is known as Stokes shift. It is due to the loss of energy between the time a photon is absorbed and when it is emitted.
The hypothesis stated that when the spinach extract was placed on the polar paper chromatography the pigment would separate into different pigments on the...
When the light emitted from the lamp is focused on the grating, it scattered according to its wavelength. The diffraction grating angle is adjusted according to the required wavelength. Then that light passes through half mirror and it splits into two rays, one passes through reference-side light-receiving section and the other ray passes through flow cell. The difference in intensity of light can be determined between light from reference cell and flow cell, the output obtained as absorbance. UV detector detects all the components with high sensitivity. The schematic diagram of UV detector is shown in Fig.
Moreover, a future experiment is to determine the effect that the distance between the lamp and the solution has on the rate of photosynthesis. Several experiments with a similar setup to this experiment that vary the distances between the lamp and solution could be used to test this.
To continue the experiment further I can use a different source of light to test the intensity of light. For the food coloring experiment, I could use a different food color such as yellow or orange to test.
In chemistry, Colorimetry is used a lot. They use it for things such as colour painting, food manufacturing, and textiles. Colorimetry can also be used to measure light. The amount of light absorbed is called and also is measured as the absorbance which is a use of the coloured solute concentration. To use a colorimeter, different kinds of solutions have to be made, this includes a regulator or orientation of identified concentration.
As stated before, ink is made of components with varying polarity and in order to separate these components we must determine the liquid and stationary phase that does this best. One of the three suspected inks is extracted with a 50% ethanol mixture and dotted onto 7 pieces of paper to be dipped in varying solutions. Each solution varies in polarity with the stationary phase held constant (paper). The solution with the greatest separation of the components within the ink will then be used on a TLC plate (polar) to test all four inks (3 suspected inks a...