Microscopes are used to show the internal structure of materials. They also give biologists/ physicist the power to magnify and distinguish objects that are not visible by the human eye.
Microscopes How can we find out the structure of several materials? For instance wood, the grains of wood reveal its structure. But there are certain materials where the structure cannot be seen by the human eye or felt. For example a coin or a piece of rubber will appear "smooth" to the naked eye. Microscopes are used to show the internal structure of materials. They also give biologists/ physicist the power to magnify and distinguish objects that are not visible by the human eye. Light microscopes have improved the knowledge in biology, biomedical research and materials science. Light microscopes can magnify objects up to 1,000 times, revealing microscopic details. The light microscope, so called because it allows visible light to detect small objects, is probably the most well known and well-used research tool in biology. Light Microscope They reflect light off an object. Light microscopes are like magnifying glasses, in ways like increasing the size of the object. They have limited resolving power, it is 250nm, and so even if the object is placed as close as possible they image will be seen as a single, blurred object through the light microscope. Electron microscope When light microscopes were used anything smaller than 250nm could not be seen, so the only possible solution was to use radiation that has a shorter wavelength than light. Better solution was to use
Investigating the Power of a Diverging Lens
Investigating the Power of a Diverging Lens Aim: To find the power of a given diverging lens by using a pre-selected converging lens. Outline: The power of two lenses placed together in line to an object will allow both of their powers to add together. P1 + P2 = Ptotal Therefore, by using a combination of 2 lenses, one of which the power is known, I can find the focal length of the combination of lenses and then calculate the total power. The power of the converging lens can be subtracted from the total power to find the power of the diverging lens. Variables: Independent: Object distance Dependent: Image distance Control: Object size and shape, power of both lenses, material of both lenses In my pre-tests, I have found that I obtain a reasonable range of results using a converging lens of 10 Dioptres that is larger than the power of the diverging lens therefore giving reasonable results. Method: . Set up apparatus as shown in diagram. 2. Adhere the unknown diverging lens to the known, pre-selected converging lens with plasticine ensuring that the plasticine does not interfere with the light i.e. the plasticine does not cover the main central portion of the lenses. 3. Fix the lenses on to the stand with plasticine, making sure that they are perpendicular to the ground therefore the light that falls upon the light will be in line with the normal at the centre of
Formation of Lens
Case Study: Every lens has a focal point, where all the light directed at that lens converges or diverges and the distance between the lens and that point is called the focal length. The eye normally focuses on the image on the retina. This is because the convex lens inside the eye can become wider or narrower to compress the light. Sometimes, however, something inside the eye is not functioning correctly. This makes the visualization blurry or mixed up. I am going to identify these disorders and how lenses correct them. Defects of Eye These are the different types of eye defects that may be corrected by lenses: Myopia also known as nearsightedness is one of the defects of the eye. A person who is suffering from this disease only see objects that is near to the eye clearly. This means you cannot see objects at a distance which appeared to be blurred. If the eye has myopia the eye is too long and the image falls short of the retina when the target object is far away. The image shows that in myopia the image fall short of the retina when the target object is far away. CONCAVE LENS FOR NEARSIGHTEDNESS A concave lens is a diverging lens which works similar to the convex mirror. This lens is thicker towards the edges and thin in the middle and is used in helping correction of nearsightedness. All images produced by concave lenses are virtual, erect and reduced.
To compare the growth of yeast between two yeast suspensions.
Yeast Growth under the Microscope Aim: To compare the growth of yeast between two yeast suspensions Materials: * 2 Sterile conical flasks * Non-absorbent cottonwool plugs * 50 mL of grape juice * 1 teaspoon of sugar * dry active yeast, half a packet * Bunsen burner * tripod * gauze mat * Microscope * 2 Glass slides * 2 glass cover slips * 2 dropping pipettes Method: 25mL of grape juice, and half a teaspoon of sugar was added to Flask A, then heated to boiling point for one minute. A thermometer was then placed in the flask and plugged with cottonwool. Flask A was then left to cool down to 30?C. Once the flask reached 30?C the cottonwool was quickly taken out and a quarter of a packet of yeast was added, as quickly as possible the cottonwool plug was replaced. The rest of the grape juice and sugar was then placed in Flask B and then heated at boiling for one minute. The yeast leftover was then added to the boiling mixture, plugged with cottonwool then allowed to cool. Both Flask A and B were then left at 25?C overnight. The cottonwool was then removed from Flask A and a sterilised dropping pipette was used to place a drop of the suspension onto a slide. A cover slip was then placed on top and the slide was then observed under the microscope. Cells were then observed under the low power lens and yeast was observed under the higher power setting.
Observe how a microscope can be focused on different levels of an object from its top to its bottom surface.
Liban Ahmed Experiment 3 September 20, 2003 Depth of Field Purpose Observe how a microscope can be focused on different levels of an object from its top to its bottom surface. Hypothesis The microscope can be adjusted and utilized to focus on objects that have different depths. The microscope has different depths of fields depending of the magnification. The higher the magnification the less depth of field. The lower the magnification, the higher the depth of field. Materials * Prepared slide of 1cm square pieces of several types of cloth * Microscope Procedure . Brought a microscope to the lab area making sure to use both hands to carry the microscope and that the cord was not dangling. 2. Looked through the instructions making sure there were no problems that could be posed. 3. Organized the lab area and prepared all equipment including slides and the microscope. 4. Placed the prepared slide on the stage making sure the stage clips held the stage in place. 5. Rotated the nosepiece to the low-power objective lens and carefully focused on the image. 6. Recorded observations. 7. Rotated the nosepiece to the medium-power objective lens and carefully focused on the image. 8. Recorded observations. 9. Rotated the nosepiece to the high-power objective lens and carefully focused on the image. 0. Recorded observations. 1. Removed the slide. 2.
What are Light Microscopes?
Pass1 What are Light Microscopes? What does the word microscope mean: The first part of the word "Micro" means tiny. The "scope" part means to look at or view. Microscopes are tools that are used too enlarge images of small objects so that they can be studied. A light microscope is an instrument made up of two lens they are eyepiece lens and the object lens combined they produce a much greater magnification that what is possible with just one single lens. The microscope also has a variety of knobs to focus the picture seen thought the microscope. The light microscope is also known as the compound microscope this is because it uses more than one lens. The light microscope uses visible light to detect small objects; the microscope consists of an optical instrument that magnifies the image of an object. It is probably the most used research tool in biology. The total magnification is calculated by multiplying the magnification of the two lenses inside the microscope. Images looked at under the light microscope are reversed and inverted. Functions Of The Components Seen Under A Light Microscope Cytoplasm: is a partly fluid material, which can flow slowly and in which many other substances are suspended such as large fat and protein molecules. Many of the chemical reactions take place in the cytoplasm, which will provide the cell with energy and allow it to build up
ELECTRON MICROSCOPY This is the act of using electron microscopes. Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale. Electron microscopes can be used to view the topography (surface), the morphology (the shape and size of the particles making up the object) and also the composition (elements and compounds the object is composed of and how many: in case of cell organelles). Electron microscopes were introduced or developed due to the limitation of light microscopes. This is because the resolving power of a microscope depends on the wavelength of the electromagnetic radiation used; because the light microscope uses only the visible part (light) of the electromagnetic spectrum whose shortest wavelength is 400 nanometre (violet light), therefore objects smaller than half of the wavelength (200nm) cannot be viewed using a light microscope. E.g. cell organelle ribosome is 20nm and can never be seen using a light microscope. As electron microscopes uses electrons, which are negatively charged and beams of electrons have a very short wavelength. This type of microscope has a very high magnification and resolution power. They are two major types of electron microscopes the first type originally developed: The Transmission Electron Microscope, which is quite similar to the light electron microscope
Comparing the Light and Electron Microscope
Comparing the Light and Electron Microscope In this essay I am going to be comparing the light and electron microscope, I will look at the advantages and disadvantages of each microscope and then analyse my findings to see if one is better than the other. The light, or optical microscope as it is also known was invented in the 17th century, it has been refined in many ways over the years but it is essentially still the same. The light microscope works by; light rays from a light source beneath the stage are through to glass lenses in series. The two lenses are called the objective lens and the ocular (eyepiece) lens. Depending on their strength these two lenses on their own routinely provide magnifications of up to 400 times. There is a limit to the amount of detail the light microscope can show, this limit is set by the resolving power. The resolving power is the minimum distance by which two points must be separated in order for them to be perceived as two separate points, rather than a single fused image. For the light microscope this distance is approximately 0.2µm. So in theory it might seem possible to magnify an object indefinitely by means of glass lenses in series. This has been put into practice and has only produced a larger and fuzzier picture; so the resolution is not improved and no more detail is visible. The resolution of the light microscope is imposed by
When two objects are placed close enough to each other or are a great enough distance, there will come a point where your eyes will be unable to distinguish the two objects apart. Determine the resolving power of your eyes.
Liban Ahmed Experiment 4 September 20, 2003 Resolving Power Purpose When two objects are placed close enough to each other or are a great enough distance, there will come a point where your eyes will be unable to distinguish the two objects apart. Determine the resolving power of your eyes. Hypothesis If two strands of hair are placed a foot away in front of white background, then the resolving power of the eyes will be approximately half a millimeter or 0.5 mm. Materials * Glass slide and cover slip * Two human hairs * Dissecting needles * Microscope Procedure . Brought a microscope to the lab area making sure to use both hands to carry the microscope and that the cord was not dangling. 2. Looked through the instructions making sure there were no problems that could be posed. 3. Organized the lab area and prepared all equipment including slides and the microscope. 4. Placed two human hairs on the slide 1 mm apart and placed the cover slip above. 5. Placed the slide in front of a white background and examined from a distance of one foot. 6. Determined if the two hairs were distinctly separate and recorded observations. 7. Moved the hairs closer together using a dissecting needle and recorded measurements. 8. Determined if the two hairs were distinctly separate and recorded observations. 9. Repeated step 7-8 until the hairs could not be
My experiments focus is to obtain an accurate measurement for a specific lenss power.
Quality of Measurement Coursework: 'The power of a lens' Andrew Ensten Aim My experiments' focus is to obtain an accurate measurement for a specific lens's power. This will be achieved by focusing on the lens equation: /v (curvature of wavefront after lens) = 1/u (curvature of wavefront before lens) + 1/f (power of the lens/curvature added by lens). By performing an experiment with a source of light, a lens, and a screen, I will obtain several 1/u and 1/v values. When these values are plotted on a 1/v against 1/u graph, they will hopefully give me an accurate estimation of the power of the lens by looking at the axes intercepts. Equipment: * Power pack: For each experiment I kept the output setting to 9 Volts to control the power being delivered to the filament lamp (as power = current x voltage). Power is proportional to intensity and so a brighter/darker output could result in a different range where the created image is in focus. * 2x Wires: These took the electric current from the power pack to the light source I was using. * Filament lamp: I chose a filament lamp over other sources of light as it is easy to tell when its' image is formed. This is because the filament is a very definable object. I used it for my first, third and fourth experiments. With a constant voltage output; the intensity of light was relatively constant. * Light Emitting Diode: I