The Compact Disc.
The Compact Disc The compact disc if by far one of the most revolutionary mediums to have been invented in recent times. It has completely changed society in a numbers of ways and has benefited everyone. In this coursework I aim to discover how a CD is produced, written on and how it is read inside a CD-ROM. I will also be looking at the difference between a CD-R and a CD-RW. The average CD-R or RW can hold about 6 billion bits of binary data. This is about 780 megabytes of data, and at 2000 characters per page an average CD can store up to 275,000 pages of text. A CD can also hold about 74 minutes of audible music as it samples at 44.1kHz. The first aspect I chose to look at was how a CD is produced at a manufacturing plant and what materials and components go into making a CD. A CD is made up of a number of components. Its base material is polycarbonate; it is what makes the CD strong and provides a surface for other layers to be applied to. A reflective layer is then applied to the surface of the polycarbonate using a process called sputtering. This is a shiny layer that is used to bounce the laser beam back to its original source. This means that this layer must have a very high integrity so that it remains in shape and not break apart. This reflective layer is usually made up of silver, but on occasions it is made up of gold or platinum. With a CD-R and CD-RW there is
Physics of Music - How a guitar works.
Physics of Music How a guitar works A typical guitar has six strings. These are all of the same length, and all under about the same tension, so why do they put out sound of different frequency? If you look at the different strings, they're of different sizes, so the mass/length of all the strings is different. The one at the bottom has the smallest mass/length, so it has the highest frequency. The strings increase in mass/length as you move up, so the top string, the heaviest, has the lowest frequency. Tuning a guitar simply means setting the fundamental frequency of each string to the correct value. This is done by adjusting the tension in each string. If the tension is increased, the fundamental frequency increases; if the tension is reduced the frequency will decrease. To obtain different notes (i.e., different frequencies) from a string, the string's length is changed by pressing the string down until it touches a fret. This shortens a string, and the frequency will be increased. Wind instruments and longitudinal standing waves Pipes work in a similar way as strings, so we can analyze everything from organ pipes to flutes to trumpets. The big difference between pipes and strings is that while we consider strings to be fixed at both ends, the tube is either free at both ends (if it is open at both ends) or is free at one end and fixed at the other (if the tube is
Investigation into the Strength of an Electromagnet
George Maund Investigation into the Strength of an Electromagnet Planning Experimental Procedure When electric current is passed through a wire a magnetic field is created. If you wind the wire around an iron core, then you have an electromagnet. They have North and South poles just like normal magnets, but it does have some differences - if you switch off the current, the magnetic field is lost, and the strength of the magnetic field can be altered by either changing the number of coils around the core, or by changing the current. I intend to measure the strength of an electromagnet - a magnet consisting of an iron core with plastic-coated wire rapped around. When current is applied through the wire, the iron core becomes magnetic - and I intend to test the effect of varying the current. The factors that will have an affect on the quantity I'm investigating include room temperature, material of core, number of coils around the core - I intend to keep all of these constant. The factor I intend to vary in my investigation (independent variable) will be current - the current flowing through the coils of the electromagnet. I have chosen this as I think it will be the easiest to investigate and carry out. The other variables (number of coils) will be kept constant so as to give valuable and worthwhile results. Prediction My prediction is that the amount of current passed
The aims of this investigation are to find the relationship between the angles of incidence and the angles of refraction for a transparent material and to find the critical angle of the transparent material.
Physics GCSE Coursework- Refraction of light The aims of this investigation are to find the relationship between the angles of incidence and the angles of refraction for a transparent material and to find the critical angle of the transparent material. Refraction is the bending of light rays that occurs when they pass from one transparent material, or medium, to another. When light passes from a less dense medium (for example, air) to a denser one (for example, glass) it is refracted towards the normal (an imaginary line perpendicular to the surface). This occurs because the light waves are slowed down by the denser medium, causing them to change direction. On leaving the glass block, exactly the opposite occurs: the light is refracted away from the normal on passing back to the less dense medium. One everyday effect of refraction is that objects seen under water appear to be at a shallower depth than they really are. The observer sees an underwater object in a higher position, because the eye cannot tell that the light has been refracted on its path from the object. Due to light travelling from a denser to a less medium is refracted away from the normal, some rays striking the surface at a larger angle of incidence (angle between the ray and the normal) cannot pass through it, as they would have to emerge at an angle greater than 90 degrees, which is not possible. Such
What factors have an effect on the strength of an electromagnet?
What factors have an effect on the strength of an electromagnet? In my investigation, the one thing that I am going to change by equal amounts each time is: Voltage In my investigation, the thing I shall measure - that is affected by my change is: The strength of the electromagnet To make it a fair test, here is a list of things I shall keep the same: * Number of coils (15) * Battery pack * Iron core * Clamp stand * Paperclips Apparatus~ Here is a list of everything that I shall need to do my investigation: * 1 Battery pack * 1 Iron core (nail) * 1 clamp stand * plastic insulated wires * 1 box of standard sized paperclips Prediction ~ What I think will happen: I think that in my experiment the more I increase the voltage the stronger the electromagnet will be. Why I think this will happen: I think this will happen because voltage adds current to the wire around the iron core, which make it become magnetised, making it an electromagnet. The more current I add the stronger the strength is because there are electrons (electricity) moving through the wire and are causing it to have a magnetic field. The more electrons moving through the wire, then the bigger and stronger the magnetic field around the wire is going to be. One of the reasons that I know that there is a magnetic field around a wire when electricity runs through it, is because* Christian
Outline the Factors that Influence the Amount of Wave Energy that Arrives at the Coastline.
William Murdoch Outline the Factors that Influence the Amount of Wave Energy that Arrives at the Coastline The amount of wave energy that arrives at the coastline is governed by a combination of factors. By wave energy, we mean the actual amount of force a wave can exert on a body, and by coastline, we mean the interface between the land and the sea. This essay will discuss the factors involved with the gaining of wave energy. Secondly, the factors involved with the reduction of wave energy will be discussed. Thirdly, there are the directional factors and finally, the human factors. Wave energy is inversely proportional to the wave height squared. Therefore it is the factors governing wave height, which govern the gain in wave energy. Wave height is the vertical distance between the bottom of the trough and the peak of the crest. It is governed mainly by fetch, (the distance over which the same wind direction has influenced the waves) and wind speed. With a large fetch and low wind speed, surging waves are formed. These are flat, low waves of low energy. They have wavelengths of around 100 metres and a wave height of one metre or less. The wave period is very long with around six to eight wave breaks per minute. Such low energy waves would deliver low amounts of energy to the coastline. With a short fetch and a high wind speed, spilling waves are formed. They
Insulation Materials Experiment Method We put 100ml of water at 80C into each of 6 beakers. Each beaker had a different material wrapped around it, and we measured the amount of time taken for the temperature of the water to decrease by 10C to 70C
Insulation Materials Experiment Method We put 100ml of water at 80ºC into each of 6 beakers. Each beaker had a different material wrapped around it, and we measured the amount of time taken for the temperature of the water to decrease by 10ºC to 70ºC. We used a thermometer to measure the temperature of water and a stopwatch to measure tha amount of time taken. Results Time taken for each attempt (seconds) Material 2 3 Average time (seconds) Polystyrene 79 92 201 90.67 Carpet 201 90 91 94 Bubblewrap 90 225 94 203 Fibreglass 213 78 98 96.33 Tissue paper 72 69 225 88.67 Cotton 62 76 - 69 Conclusion From our results wee can conclude that bubblewrap is the best insulator tested. It took an average of 203 seconds to lose enough heat energy to the atmosphere to reduce the temperature of the water to 70ºC. The cotton material was the least effective insulator - at an average of 169 seconds it took the least time to allow enough heat energy to escape for the water temperature to fall by 10ºC. These results can be backed up by scientific explanation. Bubblewrap is an effective insulator because each of the bubbles contains air. Air is a very poor conductor of heat because the particles are so spaced out that heat, which is transferred by particles causing bordering particles to vibrate more, cannot transfer quickly through the particles.
Resonance of a Wine Glass
Resonance of a Wine Glass Final Conclusions Reached The amount of water added to a glass affects its resonant frequency. As more water is added the frequency goes down. This is because the waves lose energy when they drag water molecules along with them around the glass.1 The more water in the glass, the bigger surface area is covered, and more molecules are exposed to the dragging effects of the waves of vibration throughout the glass. All four sets of results taken show a curved trend (although some more prominent than others). Similar shaped glasses appear to produce similar frequencies and my theory is that the energy taken by the water is proportional to the air left in the glass by a factor of k/x2 where could be any constant > 1 and x could be to any power >0. Originally I thought the consistency of the liquid in the glass would affect the sound it produced as I thought stronger intermolecular bonds would mean fewer molecules would be dragged around the glass and thus the frequency would not change as much as with water. However, after two tests, conclusive results showed I was wrong and this made no difference to the frequency of sound it produced. I came to no firm conclusion about the relationship between speed and frequency. I believe this is because there is more of a relationship between pressure and frequency. However, I couldn't test this at school as the
Our aim is to find the factors, which make the strongest electromagnets.
AIM Our aim is to find the factors, which make the strongest electromagnets. APPARATUS Whilst doing this experiment, we will need the following apparatus: An iron nail, an electric current, some wire, a clamp, a boss, and some paper clips. VARIABLES To change the strength of the magnet we could change the iron core, change the number of coils, change the current, change the volts, or change the thickness of the wire. My partner and I chose to change the amount of coils around the nail, for our experiment. PREDICTION I predict that the more coils we add to the electromagnet, the stronger the magnetism will be and therefore the larger amount of paperclips the magnet will be able to suspend. So if you double the amount of coils, than the magnet will pick up double the amount of paperclips. Here is my predicted graph: METHOD NUMBER OF COILS MADE NUMBER OF CLIPS ATTRACTED 0 0 20 0 30 8 40 30 50 42 60 50 70 64 80 80 90 88 00 96 We will set-up the apparatus in the appropriate way. We will change between using an iron nail, than vary the current strength, change the number of coils in the electromagnet (apart from these we will change nothing else). We will measure the strength of the electromagnet by telling how much weight it can take. We will change the variably around and than make seven observations on how strong the current is. We could wear
An investigation into the factors affecting the frequency of a standing wave
An investigation into the factors affecting the frequency of a standing wave Introduction There are several ways in which you can control the pitch (frequency) of a note produced by a string. A string with 2 fixed ends (called nodes) can produce different standing waves. The lowest frequency standing wave that can be produced has a wavelength ? where ? = 2l (l = length of string) This is related to the frequency ƒ of oscillation by the wave equation V = ƒ? Where V is the speed of transverse waves traveling along the string. You can therefore deduct that ƒ = v/? = v/2l ƒ therefore should be inversely proportional to the length of the string, i.e. the shorter the string, the higher the note. The frequency will also depend on the tension and the mass per unit length of the string, as they affect the speed of transverse waves traveling along the string. The greater the tension, the greater the speed, and the heavier the string, the lower the speed. This becomes important in this investigation because if the experiment is to be fair, then the two other factors affecting the frequency must be kept constant for the results to be accurate. I have decided to investigate the effect that altering the length of string along which the wave travels. From the above equations, I would expect the frequency to be inversely proportional to the length of string, as you would
