#### To find out how the length of a piece of wire effects the reaction time in a circuit.

Physics Coursework. Planning: Aim: To find out how the length of a piece of wire effects the reaction time in a circuit. Background and general information: In this course work investigation I will be trying to find out if the length of a piece of wire which is joined into a circuit effects the resistance. There is many reasons why the wire may cause more or less resistance. The length, temperature, thickness and the material the wire is made out of are all factors, which will effect resistance. I have decided to test how the length of the wire effects resistance as it is the easiest experiment to perform. Temperature and thickness of wire would be far too hard to set up and changing the type of material used each time for the wire would yield small results as we could only use maybe 5 or 6 different metals. In my experiment I will only be recording the resistance from the different lengths. However the materials, temperature and thickness will still be very important, as they will still effect the resistance. I will try and keep the same wire each time simply making it shorter so it is the same material each time. AS it is the same wire the thickness won't change either. The temperature of the wire should not change either, as I will be putting the same current in for each try. I will need lots of results but not too many. To make this possible I will be removing 5

#### Electrons, photons, and the photo-electric effect.

Electrons, photons, and the photo-electric effect 8-6-99 We're now starting to talk about quantum mechanics, the physics of the very small. Planck's constant At the end of the 19th century one of the most intriguing puzzles in physics involved the spectrum of radiation emitted by a hot object. Specifically, the emitter was assumed to be a blackbody, a perfect radiator. The hotter a blackbody is, the more the peak in the spectrum of emitted radiation shifts to shorter wavelength. Nobody could explain why there was a peak in the distribution at all, however; the theory at the time predicted that for a blackbody, the intensity of radiation just kept increasing as the wavelength decreased. This was known as the ultraviolet catastrophe, because the theory predicted that an infinite amount of energy was emitted by a radiating object. Clearly, this prediction was in conflict with the idea of conservation of energy, not to mention being in serious disagreement with experimental observation. No one could account for the discrepancy, however, until Max Planck came up with the idea that a blackbody was made up of a whole bunch of oscillating atoms, and that the energy of each oscillating atom was quantized. That last point is the key : the energy of the atoms could only take on discrete values, and these values depended on the frequency of the oscillation: Planck's prediction

#### Investigation Into The Factors Which Alter The Resistance Of A Wire.

Investigation Into The Factors Which Alter The Resistance Of A Wire Aim The aim of the investigation is to find which factors alter the resistance of a wire. This means I must find out which factors alter the resistance and I can do this by firstly selecting which factors I think will affect the resistance. What I am going to investigate and why I have decided to investigate: - . The thickness of the wire that is to be used because there is a sufficient range of wires that I have available to me that can be tested. 2. The length of the wire that will be used, as there is also a sufficient amount of wire for many lengths to be tested which would provide many results. In this experiment I am not going to be testing temperature and its effect on the resistance of a wire as I feel it would be rather difficult to measure and maybe harder to compare results with other factors. Also I am not going to test the effect of the material i.e. changing the wire to copper from nichrome ass there is an insufficient range of materials available. This means that I would have fewer results to base my conclusion on and therefore my conclusions maybe unreliable. Range Of Measurements All readings of measurements will be repeated to ensure that I acquire accurate results. Changing the width, keeping length the same There will be a fixed length at 15cm. The thicknesses of wire that I will

#### An investigation of the factors that affect the resistance of a wire

An investigation of the factors that affect the resistance of a wire Plan Metals conduct electricity because the electrons in the metal can move about inside the structure. Wires can be made of different metals - and the reason why they give different resistances is all down to the number of "free" electrons there are in that metal - these are electrons that aren't involved in bonding, and are "left over". Current, is the flow of electrons around a circuit. Those materials, which have a lot of "free" electrons, will make it a lot easier for current to flow through, and so there is low resistance. That's why not all metals are equally as good at conducting electricity. The other things that can affect the resistance of a wire are length; a longer wire will make it more difficult for current to flow, as there is more material to travel through therefore the resistance increase. The cross sectional area; the larger this is, the more charge can travel at the same time through a given length, so the resistance decreases. To calculate the resistance of a wire I will need to use the following formula: R= V/ I V= Potential difference in volts (V) I = Current in amps (A) R= Resistance in a unit called and ohm () Preliminary testing: I have already done some preliminary investigations, testing the different types of wire such as copper and nichrome, and most

#### Energy transformation in a bouncing ball

Energy transformation in a bouncing ball Planning Aim To investigate the energy transformation in a bouncing ball. When a ball is held above the ground it possesses Gravitational Potential Energy (GPE). When it falls down, because of the force of gravity, it loses Gravitational Potential Energy but gains Kinetic Energy and some loses by heat. This tells us that 'Energy cannot be created or destroyed but can only change from one form to another'. Now I am going to find out what proportion of the energy is lost during a bounce and to see if there is a pattern. Prediction After the ball bounces, it gains elastic energy, with this energy, it moves upward and gain Kinetic energy which is converted into GPE until the ball reaches the top of its bounce whereupon the whole process is repeated. But each time when the ball bounces, some of the energy is lost by heat and sound energy during the time coming down and when it hits the ground, and also because of air resistance, so that the ball will not reach the height it was released from. As we know that the air resistance will not change and each time when the process repeats, the ball become more near and near the surface, so that the GPE will also decrease. Each time when the ball bounce, the energy will lose in percentage, because different height the ball release, it will have different amount of energy, so that I predicted

#### Investigate how the height a ball is dropped from affects the re-bounce of it.

Alice Tilton Physics Coursework February 2004. Aim - To investigate how the height a ball is dropped from affects the re-bounce of it. Equipment - meter ruler stick - I chose this because it was more accessible and something else like a tape measure would not be reliable as it is not solid and can move more easily. I will use this to measure the bounce of my ball. squash ball - I am using this because it was available and has a smooth round edge so it will bounce straight back upwards. This will be the ball I use in the experiment. stand and clamp - I have chosen this so that it can hold up the ruler straight and not move it around like a person would. This will hold up the ruler straight. Diagram - Preliminary work has shown that the squash ball gives more reliable results compared to other types of balls, and works best on a hard surface. I plan to measure the re-bounce of a squash wall when dropped vertically from various heights; this will show me the how the height a ball bounces depends on its drop height. I will do this by using the planned procedure below: Method - ? Firstly, set up the apparatus, ensuring that the ruler is perfectly straight and that it is the right way up - 0-100 from the bottom of the surface. ? drop the ball from the first point and record the height the ball bounces back up to. ? repeat this till all the desired dropping points

#### Experiment is to investigate different lengths of wires and see if the resistance changes.

Resistance of wires Theory: The theory of the experiment is to investigate different lengths of wires and see if the resistance changes. What is resistance? The resistance is a measure of how easily the electrons can move through a metal. A low resistance means that the electrons can move easilly and a high resistance means electrons cannot move around as easilly. The resistance can be found out by dividing the voltage by the current. How is the resistance measured? The resistance (R) of a length of wire is calculated by measuring the current (I) present in the circuit, and the voltage (V) across the wire (at the same time) The measurements are then applied to this formula: R = V I What is the current? The current is a measure of the charge that flows per second. Current=charge/time Since the charge on each electron is the same, the current represents the number of electrons flowing per second. If the resistance is high, the flow of electrons is slowed down and so the number of electrons per secon is reduced.is.the current is reduced. Equiptment: .ruler with wire attached .wires and crocodile clips .Power supply .Voltmeter and Ammeter The equipment should be set up like this: Method: . Set all the equipment up as the diagram shows above 2. Turn the power onto 3 Volts 3. Using a crocodile clip and scan each of the measurements. Starting at 0cm and

#### My investigation will aim to show how the resistance of a wire is altered with the length of the wire.

Physics Investigation; Testing Resistances Jack Burnham 10C (2001) Planning; The Investigation: My investigation will aim to show how the resistance of a wire is altered with the length of the wire. Equipment List: For the experiment I will need; An Multi-meter / Ohmmeter, A large amount of "Constantan wire", Normal Wire, 2 Crocodile clips, Some Cardboard, A Ruler, A Wire-cutter. Prediction: I think that the length of the wire will affect the resistance. My prediction is that the longer the wire, the higher the resistance, this is also what Encarta online encyclopaedia thinks. (http://encarta.msn.com/) Method: Firstly I shall secure the wire on to a piece of cardboard, making sure that it is securely fastened to the cardboard, and pulled out taught. Then I will write the measurements on the cardboard, parallel to the wire, so that the measurements are exactly correct. Then I will affix one crocodile clip to the start of the wire, and secure it in place. Then I will have one more crocodile clip, but move it to different measurements, to test the resistance if the wire. I will record my results and analyse them. How I will make it a fair test: I will ensure a fair test by making sure firstly that the wire is very taught, and that there is no tension in it, thus making the measurements exactly correct. I will also have to make sure that the first crocodile

#### Resistance in Nichrome Wire.

Resistance in Nichrome Wire Aim: To investigate the resistance of Nichrome wire. To find out how the length of a wire affects its resistance. Plan: Background information: Resistance is the force, which opposes the flow of electric current round a circuit so that energy is required to push the charged particles round the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long e.g. the filament across an electric bulb. Resistance is measured in Ohms (~). A resistor has a resistance of one ohm if a voltage of one volt is required to push a current of one amp through it. The total resistance of resistors in series is the sum of the resistance of each one. George Ohm discovered that the electromotive force or potential difference of a circuit is directly proportionate to the current flowing throughout the circuit. He also discovered that a circuit sometimes resisted the flow of electricity. He then came up with a rule for working out resistance. Resistance is equals to Voltage divided by current and the formula could be written like this: This also tells us how to work out the current and voltage using other information. Therefore if I have a voltage of 6 volts and a current of 2 amps, my resistance will be 3 ohms. Resistance is shown to depend on the type of metal. The metal is shown to be a lattice of positive metal

#### In this investigation I will investigate the relationship between the length of wire and amount of resistance.

Investigation into the resistance of wires Aim In this investigation I will investigate the relationship between the length of wire and amount of resistance. Planning In this investigation I will choose 10 evenly spaced pieces of wire, do 3 tests per length, find an average and put the data into a table. Prediction I predict that if the length increases then the resistance will also increase in proportional to the length. I think this because the longer the wire the more atoms and so the more likely the electrons are going to collide with the atoms. Therefore, if the length is doubled the resistance should also double. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. My graph should show that the Length is directly proportional to the resistance. If the length of the wire is only half the length of the wire on the same type of wire, there should be half the number of collisions between the electrons and the atoms. If the wire is twice as long, there should be twice the number of atoms, resulting in twice as many collisions and a predicted doubling of the resistance. Safety * Handle the power supply carefully. * I am going to only use a voltage of four volts so the wire will not burn * Be careful when touching the wire, as it may be