Internal resistance investigation - I will conduct the following investigation with the aim to find the internal resistance of a lemon battery, which I will construct myself.
AS Physics - Internal resistance investigation I will conduct the following investigation with the aim to find the internal resistance of a lemon battery, which I will construct myself. The variables that could affect my experiment are as follows: * Size of lemon - I will conduct my experiment in no longer than an hour, allowing me to use the same lemon for all results * Size of metal electrodes - I will use the exact same electrodes throughout the whole experiment * Length of any connecting wires - I will use the exact same wires throughout my experiment and will not break the circuit once I have started collecting data * Resistance in the circuit - I will vary this using a highly sensitive variable resistor as shown in my method. To make my experiment fair I will only vary the most relevant variable to what I am investigating, which is the resistance in the circuit. All the other variables will be kept the same throughout the experiment as stated above. In my experiment I will need to measure the terminal pd, V, and the Current, I (in amps), for many values of resistance, R (in ?), I will measure these as I know that V=E-Ir so these are the values that I need to know if I am to eventually calculate the batteries internal resistance. I think that to make my graphs and conclusions accurate I will need to take at least 10 measurements, covering the full range of the
Measurement of capacitance by reed switch.
Physics Laboratory Report The number and the name of the experiment: Experiment 1- Measurement of capacitance by reed switch(TAS) The date of experiment:19 / 5 / 08 Objectives * Use a reed switch to measure the capacitance of capacitors. Apparatus Reed Switch Variable resistor Signal generator Micro ammeter Battery Box (with 4 cells of 1.5 V each) Voltmeter 2.2 Capacitor Connecting Leads Theory A reed switch is a two-way switch controlled by a signal generator as shown in Fig. C1. It can be used to charge and discharge a capacitor by connecting it across a power supply(point B) and a micro ammeter (point C) alternatively. When the reed switch connects the capacitor (C) to a power supply (V), the capacitor charges and stores electric charges. A few moments later, the reed switch connects the capacitor to a micro ammeter. The capacitor discharges in which the frequency () is the signal generator frequency. When the switch touches B, the capacitor is charged to a potential differences V, which is recorded by the voltmeter. The charge on the capacitor is : When the switch is in contact with C, the capacitor discharges through the micro ammeter. This process of charging and discharging occurs times per second. In each second, pulses of charge () flow through the micro ammeter. Hence, the current () through the micro ammeter is given by : Procedures . The
Identification of purpose of physics.
Greenwich Royal Observatory Identification of purpose of physics From my visit to the Greenwich Royal Observatory, the first aspect of physics that I will be showing an understanding for is the time keeping due to the earth's movements. Time keeping is on of the most important and what make Greenwich the most famous place for the "creation" of measuring time efficiently. Everyone needs the time and that's why so many years were put into inventing the "perfect" clock. The physics behind the clock is to get an exact measurement of 1 second. This has been achieved by pendulums, weights and now by computer. Time has been completely based on the earth's movement. Early on time was just measured by the light of day but then this all changed due to the stars. In the 1700's people started to measure the earths spin by using the starts. At night the looked up and pinpointed a star. The following nigh they would wait for that start to appear in the same place. The time between this was 24 hours. This was a great result due to the fact that there were 12 months in a year and this could easily let the time "integrate" with this number. However they shortly found out that seconds were being gained and lost due to the earth spinning round the sun. This means that they need some way in keeping the time correct after years. This is here the atomic watches came in. These
What is the speed of sound waves?
What is the speed of sound waves? Prediction: I predict that the speed of sound in air will be 330m/s. Method: The apparatus were sat up as below. The metal plate was held 10cm above the start microphone. It was then hit with the hammer and the time it took for the sound to travel to the stop microphone was recorded by the fast timer in microseconds. This was done twice and then the start microphone was moved to the 90cm mark on the ruler the process was repeated until the microphones were 10cm apart. However, nothing else was changed except the distance between each microphone. Result Distance between the microphones (metres) Time for Sound to travel from M1 to M2 (microseconds) 2 Average 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 3029 2996 2094 850 561 241 941 641 393 29 3023 2725 2181 2147 472 311 892 667 387 10 3026 2860.5 2137.5 998.5 516.5 276 916.5 654 390 19.5 Analysis The graph on the previous page shows the time that was recorded for certain distances. Those distances are different from the ones stated in the results table on page 1. However this will be explained later. If we look at the graph we can see how the points that were plotted lie very close to the line of best fit, with the exception of the last two circled points, and show a positive correlation. Also you can see how the line goes through the origin, which
Refractometers visit report
Visit Report For my visit report I visited Aimia Foods, a company who specialise in producing soft drinks. I have chosen two pieces of equipment used by the company in the Quality Assurance / Research & Development Departments. Both are used to measure liquids. One of them is a polarimeter used to detect faults in essential oils and other solutions, the other is a refractometer, used to calculate the concentration of dissolved substances in water. The polarimeter is mainly used to check the quality and integrity of expensive essential oils such as lemon oil, used in the flavouring of soft drinks. It would be used on in-coming raw materials. The refractometer is much more widely used in the day-to-day measuring of syrup brix, a key quality attribute of all soft drinks. Polarimeter Polarization PHYSICS restrict vibration of light: to cause light to vibrate within particular planes, or vibrate in this way [Oxford dictionary of English] A polarimeter is a piece of equipment used in the food industry to measure the optical rotation of solutions. In this case to check for contamination/purity of essential oils, but also mixed sugar concentrations. Different solutions exhibit characteristic polarisation angles and can only pass through in two planes - 90o to one another. Light is made up of Electro-magnetic waves of many different waveforms (incoherent). When directed
Resistivity of Lightbulbs
Lower 6th Quality of Measurement: 25 January 2009 Introduction: In this experiment I am aiming to investigate how different bulbs emit different light intensities depending on the potential difference applied to them. I will create my own sensor using a potential divider circuit using a Light Dependent Resistor (LDR) along with a lux-meter to calibrate it and then collect readings. What is a Potential Divider Circuit? Potential Dividers are part of many sensors. They consist of a voltage source along with some resistors in series. The potential of the voltage source[1], for example a power supply, is divided in proportion to the ratio of resistances. This means that you can choose the resistance to get the voltage you want across one of them. In the case of this experiment, the resistance across the LDR[2] varies with light intensity thus causing the potential difference across it to vary. The other resistor in series is a fixed resistor[3] which is there to compare the resistance of the LDR thus completing the ratio. The Voltmeter[4] records the potential difference across the fixed resistor thus giving the sensor a value. As the light levels increase, the resistance of the LDR falls and thus the potential difference across the LDR falls. In turn this increases the potential difference across the fixed resistor which is measured by the voltmeter. Increasing light levels
The police force - history.
Question One The police force was invented in the nineteenth century. There were just two forces in Britain, in 1800; one was the Bow Street Runners, the other, the Thames River police force. Before the Metropolitan Police Force was set up in 1829, the streets of Britain were patrolled by watchmen and parish constables. There were also Special Constables, who could not deal with problems, such as riots (Which were common in Britain.). The Metropolitan Police Force (Or 'Met') was set up by Sir Robert Peel. These officers were a mixture of the watchmen and special constables, their duties were to patrol the streets and settle disturbances, such as riots. Sometimes, the 'Met' helped the army. There was confusion between the two forces. The British people did not like seeing the 'redcoat' uniform of the army, and so the uniform of the Metropolitan Police Force were given a new uniform. It was blue with a top hat, tail-coat, and few badges and decorations, also armed with a truncheon. These changes were made so that they would not be confused with the army. There were problems when setting up this force. Many of the recruits for the Metropolitan Police Force were dismissed, on counts of drunkenness. Also, the public did not like these officers. This was mainly because of crown control, and the way that the 'Met' handled it (Mostly by the baton charge, which resulted in the
How can I work out the Young's Modulus of copper wire?
How can I work out the Young's Modulus of Copper? List of apparatus: Physics: Variables: Method: Safety: Risk How was this reduced? Wire snapping and injuring eyes Safety goggles were worn while undertaking the experiment Weights dropping and injuring feet Moved away from weights once plastic deformation took place, visibly obvious by the wire stretching and not stopping. Weights dropping and marking floor Carpet tile was placed underneath the weights, protecting the floor from being scratched. Sources of uncertainty: Source How can the experiment be improved to combat this? Measurement of total wire length (±0.24%) A tape measure could be used to measure the length of the wire, as it would allow me to be make measurements in more awkward places, such as up the side of the wooden block. Numerous measurements could be taken and then an average could be found to give the total wire length. Measurement of extension length (±11%) I could've placed the ruler closer to the marker, so that I was able to read off the measurements with less difficulty, an optical lever could also be used to make much more precise measurements. Once again, numerous measurements could be taken to give a more reliable result. Breaking of loop The loop breaking has a massive detrimental effect on the experiment, completely voiding its accuracy. Thickness of wire (±1.8%) Taking
Use of the material Zerodur in the KECK observatory telescope. The very low CTE makes ZERODUR ideal for use as part of the primary mirror. This means that over the temperature range that is possible that the telescope works in, (0-50C), the materi
Introduction The KECK observatory lies near the summit of Mauna Kea in Hawaii. There are two telescopes close to each other on the summit, KECK I and KECK II. These combine to form one of the largest optical telescopes in the world, second only to the Gran Telescopio Canarias (GTC) in the Canary Islands. For good reason, both the KECK observatory and GTC use the same material for their primary mirrors. The primary mirrors of the telescopes are the largest mirrors of the operation, and are designed to gather as much light as possible. The bigger the primary mirror, the more light the telescope can gather, and hence the 'further' into the solar system the telescope can see. With the need to see more and more of space, larger and larger telescopes are being built. However, making a mirror with a diameter of 10 metres of more out of a single sheet of a reflective substance gives a very large problem; the mirror must be very thick in order to hold its shape. When KECK I was being designed, the engineers came up with an ingenious solution, which involved splitting up the mirror into many hexagonal sections, which, when attached together, would act as a single mirror. This meant that the primary mirror would be made from smaller sections, allowing easier maintenance, installation and construction. The mirror is made of 36 hexagonal sections, and forms a slight curve, as shown in
What effects displacement of a ray of light?
Investigation: What effects displacement of a ray of light? Variables * The angle the light hits the block at * The width of the block * The colour of the light * Light intensity Predictions * The larger the angle the larger the displacement. (See Diagram) In the diagram I have used snell's law to find the refracted angle, Snell's law is that for glass Sin i Sin r = 1.5 By using this I have been able to work out accurate results without doing an experiment. * The displacement will be directly proportional to the width of the block. I.e. The wider the block the larger the displacement E.g. if you double the thickness of the block then the displacement will double (See Diagram) Plan 1 The apparatus that I need for the experiment is Protractor 2 Ray Box 3 Ruler 4 Blank page 5 Glass block 6 Power Pack The measurements to be taken are: the size of the blocks : The size of the displacement 5 readings will be taken; this is because a large range of results is required to draw an accurate graph. A ruler will be used to measure the displacement and thickness and a protractor will be used to measure the angle. The experiment will be repeated twice to give a range of measurements The test will be kept fair by making sure that the controlled variables are kept the same throughout all the experiments. The main controlled variables are: Colour of light-
