Decay of charge
Experiment C12 (Physics TAS) 16-5-2006 -Decay of charge- Long Report Shek Pok Man, Dominic F.6B (24) Objective: Using an ammeter to investigate the decay of charge in a capactior and plot a decay curve of a capactior by using the data. Apparatus: - Battery 9V - Resistance substitution box - Voltmeter - Milliammeter 1 mA - Capacitor (eletrolytic) 470 F - Clip component holder - Stop-watch - Switch - Connecting leads Theory: In the experiment, the change of the charge on the capactior and the change of the discharge current during discharge are investaged by using an milliammeter. When a capacacitor C is discharged through a resistor R, the capacitor and the resistor have the same potential difference: (Theory) Q/C = IR (Q: charge on the capactior, I :discharge current) Q = CRI = -CR(dQ/dt) (dt/CR) = -(dQ/Q) Q = Q0e(-t/CR) (Q0 is the initial charge) The charge on the capactior decays exponentially against time. I = V/R = Q/CR = (Q0/CR) e(-t/CR) = I0 e(-t/CR) Therefore, the discharge current is also decay exponentially against time. The product of resistance and capacitance, CR, is called the time constant. The time taken for the charge (or current) to decay to half of its value is called half life t1/2 , It can be dervied that the half-life of the decay of the charge is given by t1/2 = 0.96CR. By solving Q = Q0 e(-t/CR) and Q = (1/2)Q0 We
In this coursework, I will be analyzing and proving that although metallic conductors are good conductors of electricity, they are affected by resistance.
PLANNING In this coursework, I will be analyzing and proving that although metallic conductors are good conductors of electricity, they are affected by resistance. But there are factors affecting the resistance of a conductor, and through my experiments I am going to prove that. CONDUCTORS We know that there are two types of conductors of electricity. Good conductors and bad conductors. Good conductors are that which conduct electricity the best. There are also some conductors, called semi-conductors, since they only half conduct the electricity that is passed through them. However, there are some materials, which resist the flow of electrons more that others do. These bad conductors are called insulators. Insulators are not needed to prove the factors affecting resistance, since they will be very invaluable, as they do not conduct electricity in the first place. When we talked about conductors conducting electricity, the very first question that comes up into our head is, 'How do conductors conduct is electricity?' In order to understand this, we have to learn about the structure of a metal, and to go deeper into it. Every piece of metal is made of electrons in the shells around the nucleus, which contains the protons and neutrons. Thus the atom is stable when it has the same number of electrons and protons. But when we examine a piece of metal closely, we can see that
My prediction for this experiment is that the longer the length of the wire, the higher the resistance and the shorter the length of the wire, the lower the resistance.
Science Coursework - Electricity: Resistance Introduction: In this experiment I am going to investigate the length of a wire. Prediction: My prediction for this experiment is that the longer the length of the wire, the higher the resistance and the shorter the length of the wire, the lower the resistance. What Will I Change? The only thing I will change in this experiment is the length of the wire. What Will I Keep The Same? The things I will keep the same in this experiment are the thickness of the wire, temperature of the wire and also the number of batteries used. Preliminary Work Apparatus List: * 2 leads * 2 crocodile clips * 1 ruler and wire * I multimeter Method: I connected the end of each lead into the multimeter. Then the crocodile clips were added on the other ends of the leads. Then we moved along the 100cm wire every 20cm. We then did this three times. Results: Length of wire Test 1 Test 2 Test 3 Average Resistance (cm) R R R R 20 4.5 4.5 4.4 4.46 40 8.2 8.2 8.2 8.2 60 2.1 2 2 2.03 80 6.1 6 6 6.03 00 9 8.9 9 9 To find the average resistance, the equation I used was: Average = Resistance Test 1 + Resistance Test 2 + Resistance Test 3 3 Apparatus List: * 5 leads * 2 crocodile clips * 1 set of batteries * 1 voltmeter * 1 ammeter * 1 ruler with wire Method: First we collected the leads and then
Investigating how the length of wire affects its resistance
Investigating how the length of a wire affects its resistance Aim: To find out how changing the length of a wire will affect its resistance. Introduction Electricity is conducted through a conductor by means of free electrons. An electric current is made up of charged particles that flow called electrons. They move through a conductor, e.g. wire. The more free electrons in a conductor there is, the better it will conduct electricity as more mobile electrons mean more flow. Conductors of different materials have different amount of free electrons, therefore, some conductors conduct electricity better than others. Resistance is what opposes the flow of current, (obstruction offered by the wire) and is measured in ohms, with the Greek symbol: ?. Resistance makes it difficult for the flow of electrons through the conductor. It can be caused electrons colliding with atoms in a conductor, obstructing the flow. Electrons will also collide with each other if there is little free space in a conductor, and so resistance will increase. Resistance can be affected by several different factors, such as light, temperature, width of wire, cross section area of wire, as well as the length of wire. In this experiment, I am going to investigate how the length of a wire will change its resistance. I will be using a range of wire lengths to test this. Formula: Resistance=
Investigating the young modulus of a wire
Introduction The aim of this investigation that I am about to carry out is to undertake a stress-strain analysis (Young Modulus) of a wire found on an ancient mummified Persian princess who according to one translation is a daughter of the King Xerxes which was about 2,600 years ago. After I have found the young modulus of the wire, I would then by comparison of the young modulus of other materials wires, conclude whether the wire found on the mummy is made from a modern alloy. Background Information (Theory) Stress is defined as an internal force produced by application of an external load. It is the relationship between the applied force and the area over which it acts. Stress(?)= applied force per unit area = = The definition and symbol for stress is also used for tensile stress (when a sample is pulled) and for compressive stress (when a sample is squashed). The SI of stress is the pascal (Pa) or Nm-2. The stress needed to break a material is called the compressive or tensile stress and is a measure of the strength of the material that does not depend on the size of the sample. If a force is applied over a surface area, there would be stress applied to the body. The shape of the body changes as a result of the applying stress. To measure this change, the size or shape of the body after the force is applied is compared with the size or shape of the body
Resistance Aim: my main aim is to investigate the factors that affect the resistance in a conductor, in which here I am using a nichrome wire.
What factors affect the resistance of wire? Aim: my main aim is to investigate the factors that affect the resistance in a conductor, in which here I am using a nichrome wire. The focal factors that affect the resistance in a conductor are: * Length * Temperature * Cross- section area * Material Hypothesis: I think that the more the cross-section area, the lower the resistance in the conductor or the nichrome wire will be. This is because the resistance happen due to the movement of the electrons through the material ( once a voltage has been applied ) they collide with the atoms in the material and as a result lose some of their energy. The idea of resistance is simply how difficult it is for the electrons to move through a material. The more difficult it is, the more energy they lose in the material on their movements. The definition of an electrical resistance is the ratio of voltage to current. The equation we use to find the resistance from the current and voltage is: Resistance (R) = Voltage (V) / Current (I) To put it in a simpler way, it is the number of volts difference across the object when one amp of current flows. It should be remembered that voltage is the number of joules of energy transferred by one coulomb of charge, and that current is the number of coulombs of charge passing a place each second. Now what the object is made of this means its
resistance of a wire
Aim The aim of this coursework is to investigate how the length of a constantan (18SWG) wire affects the resistance in a circuit. Preliminary Testing Before I can conduct the experiment I need to investigate further into what I am going to do for the investigation. By doing the preliminary testing I can find the easiest and the best method of doing the experiment. I can also make any alterations to the investigation. The first problem I had was the material that I was going to use as a conductor. I decided to choose constantan wire because it is cheap and it is easily found. Another reason for choosing this was because the resistivity was not that small or large to work with. The table below shows the possible materials we could have used. Material Resistivity/m Silver Copper Aluminium Iron Constantan Mercury Germanium Alumina Pyrex Fused Quartz The next decision I had to make was the type of constantan wire we could have used. I chose to use 18 SWG because its diameter was not to small and not to large. I had other alternatives as well the table below shows this. S.W.G 6 8 20 22 24 26 28 30 32 34 36 38 40 Diameter (mm) .62 .25 0.91 0.71 0.56 0.46 0.38 0.32 0.27 0.23 0.19 0.15 0.12 Now that I have decided on my apparatus I now need to work on the factors. There are many factors that could be taken in to account. I
The topic of which I have been studying is energy transfers, how energy can not be destroyed but only changed into another such as potential into kinetic, this the energy transfer which shall take place in my investigation.
Science Course Work Introduction The topic of which I have been studying is energy transfers, how energy can not be destroyed but only changed into another such as potential into kinetic, this the energy transfer which shall take place in my investigation. The aim of this investigation it to find out how the height of the ramp affects the speed the ball travels. Plan I am going to investigate how the height of a ramp affects the speed of which a ball travels. To make sure my test is correct I will need to keep several things the same these are: The distance the ball has to role, to get the speed. The length of the ramp. The ball, so that is the same mass and the surface so that the texture of it will be the same. The thing I will be changing is the height of the ramp. To do this I will use a ramp, a bouncy ball, a meter ruler, a stop watch and a clamp. All these will be provide by school. I will start by raising the ramp at 0.20 meters intervals using the clamp, starting at 0.20 meters and finishing at 1 meter. First I will mark a meter on the bench from where I will hold the ramp. After I have measured the 0.20 meters height I will roll the bouncy ball down the ramp and time it once it has reach the foot of the ramp and stop the stopwatch once the ball has reached the meter mark. I will do this three times so that my results are accurate and then find my
I chose to do my sensors project about sliding potentiometers because they are very common in every day life, and I thought it may be interesting to discover how they work.
Physics coursework Introduction I chose to do my sensors project about sliding potentiometers because they are very common in every day life, and I thought it may be interesting to discover how they work. There are potentiometers on lots of everyday household appliances, sliding and rotary potentiometer on hi-fis to change the volume or tuning, washing machines and dishwashers to change settings and other electrical equipment and machine. As the world becomes more computer reliant sensors will be used more often, especially potentiometers as they are easy to operate. Rotary and sliding potentiometers both work in a similar fashion. As the slider gets moved along, the voltage increases as the potential difference changes. A rotary potentiometer works the same way, but is twisted round, so rather than measuring displacement, degrees are considered. I will take this simple idea and look into true values and patterns. Plan Fig 1. Circuit diagram of the circuit to be built.(Not to scale) I am going to build the diagram as shown above and slide the potentiometer along and see what the different readings of the voltmeter are. The equipment I shall be using is: * Wires x 4 * A 59mm sliding potentiometer (5kB) * A digital voltmeter, Rapid 212 DMM. Reading error: 0.005V * 30cm Ruler. Accuracy: 0.5mm * Stopwatch, Unilab Accuracy: 0.005 secs * Power Pack (1kWIN L.V power
Investigating how the length of a piece of wire affects resistance in a circuit.
Stephanie Wickers 1st July, 2003 Investigating how the length of a piece of wire affects resistance in a circuit Aim Resistance is measurement which describes how difficult or how easy it is for an electron to flow through a conductor in a circuit. Resistance is measured in Ohms. In this investigation I am going to be trying to find out and do further research into why resistance is affected by the length of a piece of wire. Research There are many factors effecting resistance in a circuit and the four main ones are Length, Temperature, Material, and Thickness. I have done research to find out how and why these factors affect resistance. If the length of the wire is increased then the resistance will also increase proportionally. This happens because the electron has further to travel in the circuit and therefore there is more chance of a collision between an atom and an electron. If the thickness of the wire increases then the resistance will decrease and if the thickness decreases the resistance will increase. This is because the increase in area will enable the electrons to move around more freely. This in turn will reduce the number of collisions between atoms and electrons and will lower the resistance as the flow of electrons is not interrupted as much by the atoms in the wire. If the wire is heated the atoms in the wire will vibrate due to the increase
