Ohm's Law coursework
GCSE Physics- Ohm's Law coursework Aim: I have chosen to investigate how the resistance of a wire is affected by the length of the wire. What is resistance? Electricity is conducted through a conductor, in this case wire, by means of free electrons. The number of free electrons depends on the material and more free electrons means a better conductor, i.e. it has less resistance. For example, gold has more free electrons than iron and, as a result, it is a better conductor. The free electrons are given energy and as a result move and collide with neighboring free electrons. This happens across the length of the wire and thus electricity is conducted. Resistance is the result of energy loss as heat. It involves collisions between the free electrons and the fixed particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are carrying into heat. How is it measured? The resistance of a length of wire is calculated by measuring the current present in the circuit (in series) and the voltage across the wire (in parallel). These measurements are then applied to this formula: V = I ´ R where V = Voltage, I = Current and R = Resistance This can be rearranged to: R = V I Ohm's Law It is also relevant to know of Ohm's Law, which states that the current through a metallic conductor (e.g.
Do mobile phones adversly affect our health? - Case study
-------------Contents----------------------------------------------------------------------------- Pg.2 ------------------------------------ Introduction, Scientific Theory Pg.3 ------------------------------------ Mobile Phones Are/Aren't Dangerous Pg.4 ------------------------------------ Comparison, Conclusion, Bibliography Pg.5 ------------------------------------ Bibliography continued -------------Introduction------------------------------------------------------------------------ I am doing a case study for physics with the hypothesis "Using a mobile phone affects our health negatively". I have begun by looking at different websites for the facts. For example The Times article says that "The number of mobiles in Britain has doubled to 50 million since the first government-sponsored report in 2000" and the International Communications Union tells us that "About half of the world's population has a mobile phone today with mobile phone ownership worldwide topping 3.3 billion at the end of 2007". This is confirmed below. These are just a few figures that explain how serious this hypothesis is. If it does affect your health negatively, then 3.3 billion people could be at risk. I have also stated my own opinion in a conclusion and Amount of Mobile Phones worldwide - Source: IC Insights -------------Scientific
What is the best way to keep hot water hot for the longest period of time
Introduction In this practical experiment, I am going to find out what is the best way to keep hot water hot for the longest period of time. The way that this can be achieved is by preventing, Radiation, Convection and Conduction. Planning I am going to apply my background knowledge to the experiment so that it is easier to choose which items I am going to use in the experiment. Here is my background knowledge. Background knowledge I already know that heat can be lost by conduction, convection and radiation. Therefore it would be in great interest to look into these in depth as then I can see how I can prevent these from occurring. The first way I am going to cover is conduction Conduction- Conduction is what occurs in many solids. The way it is mainly passed is through the solids' vibrations. This is how the solid will look as the vibrations are passed through it. Most non-metals are not good conductors and are good insulators as they do not vibrate as much so therefore the process of conduction is very slow. Convection- The convection of heat occurs in liquids and heat only. It is a much more effective process then conduction so I am going to concentrate on stopping convection more then stopping conduction. Convection is when heat from a hot region takes the heat and moves to a cooler region. Here is a picture of what happens in the convection
Physics Argument - Is Sunbathing Good For You?
Is Sunbathing Good for You? The ultraviolet radiation (UV) in sunlight can cause skin cancer. there are many factors that can effect the risk involved when you sunbathe. Your skin tone can effect the damage caused by UV radiation because the brown pigment in skin, menalin, provides some protection. The darker your skin the more protected you are from the damaging effects of sunlight. If you have particularly fair skin, you should take extra care when sunbathing; use a suncream with a high SPF and don't stay out in the sun for prolonged lenghts of time. The amount of time you can spend in the sun varies from person to person but if you know you are proned to burning or if you have a family history of skin cancer you, too, should take extra precautions. People who have had excessive exposure to UV radiation from the sun without protection are at a greater risk from skin cancer as this is the most common cause of skin cancer. Again, you could avoid this by using suncream and not staying out for too long. Males are 2-3 times more likely than females to have basal cell and squamous cell cancers. All children should wear suncream because they have more sensitive and reactive skin than adults. Playing in the sand and swimming can remove many protection screens so it should be reapplied as often as possible, children are recomended to wear a sunscreen with an SPF of 30 or above.
Stars, Supernova and Black holes
Stars, Supernova and Black holes Stars have been around for a long time it starts from a concentration of mass in a cloud of gas and dust this started from a process of collapse. This concentration attracted matter to itself by gravity and the whole cloud started to fall in on itself. As it started to shrink, the cloud began to spin. Gas and dust were pulled in to the centre as they clashed together; it caused the temperature to rise. As the cloud collapsed more and more, it spun faster and faster, as it spinning, it flattened out until a disc formed around a central core to form what is called a solar nebula. Most of the gas and dust from the spinning cloud were released in huge plumes above and below the forming star. The pressure and temperature in the middle of the cloud eventually became so great that the atoms started to fuse releasing huge amounts of energy, and then the star started to shine. The sun is a star, like the other stars it is a ball of very hot gas. The sun gives us huge amounts of energy into space. The energy that keeps the sun shining is produced in its centre or core. The pressure in the core is enormous, and the temperature reaches 15 million degrees centre grade. Under these conditions, atoms of hydrogen gas join together to form another gas called helium. This process is called nuclear fusion. The sun is a very important star in the sky, the sun
The Simple Pendulum Experiment
The Simple Pendulum Experiment General Plan The first thing I am going to do is outline a general plan for this experiment. In this experiment, I am going to be measuring the effect of two variables on the time of one oscillation of a simple pendulum. The two variables that I have chosen are the length of the pendulum's string and the mass of the pendulum's bob. I will vary these two items and record results for the time of one oscillation of a pendulum with different mass/length of string. I must also be able to determine the value for acceleration due to gravity (hereby referred to as g) To do this, I must be able to find some equation that links length of a string of a pendulum or the mass of a pendulum's bob with time. For this I will need to carry out research. Aim The aim of this experiment is to determine the effects of two factors on the time of one oscillation (or swing) of the simple pendulum, and also to determine a value for g (acceleration due to gravity) Design Before producing a plan I will conduct a preliminary experiment this will help me find and basic flaws in the set-up of my experiment, and will also allow me to find room for improvement on my actual experiment. It will also allow me to experiment with different values for my variables, to find suitable limits to my measurements, and to find a suitable interval between my measurements of these
evolution of the atmosphere
The Evolution of the Atmosphere The present composition of the atmosphere is 78% nitrogen, 21% oxygen and the remaining 1% is made up of Nobel gases and also 0.04 carbon dioxide. As well as these there is also lots of water vapour. Here is how the atmosphere evolved: * About 4.5 billion years ago the earth was just evolving and the volcanoes gave out four things: steam, carbon dioxide, ammonia and methane. There was no oxygen around at this time. * Two billion years on from this oxygen was produced due to the green plants, which were evolving. The covered most of the earth and removed the carbon dioxide and produced oxygen. Also much of the carbon dioxide dissolved in to the oceans. More nitrogen was also produced from the methane and ammonia reacting with oxygen. * During the last billion years or so a lot has changed. The build up of oxygen has taken place and more complex organisms are around to make use of the oxygen the ozone layer has been created which blocks the suns harmful raise. The most important change would be how the amount of carbon dioxide has decrease and there is virtually none left. Today's Atmosphere The atmosphere today is perfect for us. However there is a worry that we maybe changing it for the worst by releasing various gases from industrial activity. The two main worries are acid rain and The Greenhouse Effect. Acid rain is mainly sulphur
Aim: The aim of this experiment is to see how the length of a nichrome wire affects its resistance.
Resistance in a wire Prasal. S. Rohra IX-B Introduction: Resistance is the force which opposes the flow of an electric current around a circuit. Resistance is measured in ohms (). Resistance involves collisions between the free electrons, the fixed particles of the metal and its impurities. This collision creates friction due to which some of the energy the free electrons are carrying is converted into heat. Resistance can be measured using the Ohm's Law (named after Georg ohm): - Resistance of a wire can be affected by various variables like thickness, purity, temperature, material and length out of which length is an important one. There is a direct relationship between the length of a wire and its resistance because as the length of a wire is doubled so is the resistance. As resistance is a result of collisions between the free electrons and the fixed molecules of the metal of a wire, there will be more collisions if there is a longer wire (as it is a longer path to travel for the electrons). If there are more collisions that means there is more resistance. Example: If there are 10 free electrons and have to go through 2 wires: a)10 cm and b)20 cm, there will be more resistance in wire b) as there will be more molecules in the electron's path in wire b) than in wire a). Aim: The aim of this experiment is to see how the length of a nichrome wire
What Is Fibre Optics
WHAT IS FIBRE OPTICS? To put it simply, fibre optics is a technology whereby a signal like video, data or voice, is concentrated on a light beam and sent down a glass tube over large distances, with very little distortion and loss. The principles of fibre optics are simple and easy to understand. All of us have seen the "broken straw" effect in a glass of water. When light travels from air to a denser medium, like glass for example, the light slows down by a factor equal to the optical index of the material and this slow down in speed results in bending of the light. As shown in the example when we see an object from underwater, the object is not in the actual position as we think because light bends travelling from water to air. When this angle of entry is increased, there would come a stage when the light is reflected back into the same medium, as shown in ray 3. This angle is called the angle of Total Reflection. Fibre Optics uses this simple principle for transmission. The core of the fibre optics cable, which is made of glass, has a higher index of refraction than the index of the cladding, which covers this core. So when light is injected into the glass core at the correct angle, it will reflect back from the surface and continue doing this in its forward direction of travel. In other words the light cannot "escape" from the fibre. COMPONENTS OF A FIBRE OPTICS
Radioactivity revision notes
Radioactivity Some nuclei are more unstable than others. However, they wish to become stable and do this by radioactive emissions. We can also cause or stimulate nuclei to decay by causing it to absorb a neutron. This in turn makes it unstable causing it to decay. We detect radioactive emission using a Geiger-Muller tube connected to a counter. The unit of radioactivity is the Becquerel (Bq); one Becquerel is one count per second. Radioactivity is around us all the time from a variety of sources. This is called background radiation. Radon gas 50% Ground and buildings 4% Medical 4% Food and drink 1.5% Comic rays 0% Nuclear power 0.3% Other 0.2% When measuring the radioactivity of any sample, we must always subtract a previously measured reading of background radiation from all measurements. Types of Radiation There are 3 types of radioactive emission: ) Alpha (?) - this has a helium nucleus and consists of 2 protons and 2 neutrons. It is the most massive but also the most ionizing type and can travel only 1-2cms in air before they are stopped. It is stopped by thin paper or skin. 2) Beta (?) - this is an electron emitted from the nucleus when a neutron changes into a proton. It is smaller and less ionizing and can travel metres through the air before being stopped. It requires a more dense material such as aluminium to stop it. 3) Gamma - (?? - this is an
