Static electricity and magnetism
Static electricity When materials like silk or polythene become charged with static electricity it is because they are poor conductors or insulators and the electrons stay on the surface. Good conductors like metals allow the electrons to flow away. When the charge builds up it can jump across a gap causing a spark. Static electricity happens in clouds because ice particles rub past each other and build up a charge in the cloud and this charge can jump between clouds or the Earth as lightning. Electric current Electric current is a flow of electrons along a conductor like a metal wire. Electrons come from a source like an electric cell and change places with the metal atom electrons and push the electrons of the metal atoms along the wire. The electric cell gives the electrons energy. Break the circuit and the electrons cannot flow. Electric current is not used up because electrons are not destroyed they transfer energy as they move round the circuit. This can happen in a resistor or light bulb when thermal energy and light energy are given out. Light bulbs produce light because they have high resistance and resist the flow of the electrons. Series and parallel circuits a b In diagram (a) current flows out of the battery through the ammeter and the bulbs, and as the electrons pass through the first bulb some energy is transferred. Then as the electrons pass through
Using a sensor to measure an angle.
Using a sensor to measure an angle A potentiometer or potential divider is a device, which can be used to measure certain type of data. It consists of a moving contact, which can pass along a surface of high resistance. When it does this the resistant output changes and as a result this can be used to measure things, such as distances or angles, as long as the device can be applied to either a rotary potentiometer or liner potentiometer. Current I = V/R V=voltage R= resistance I have researched that radio and hi-fi systems rely on potentiometers to adjust volume levels. On an old radio there is often a scratchy sounds as you turn the volume knob. This is because the signal from the radios is controlled by tapping off part of it with a sliding contact moving along the surface of high resistance. It works by having the signal from the radio - a varying potential difference - across the whole resistance, but the signal to the speaker is then taken from across only a part of the whole resistance. The scratchy noise on an old radio may come from dirt on the surface of high resistance, which briefly spoils the contact as the slider moves. Really top quality hi-fi equipment sometimes uses a chain of fixed resistors in between gold-plated contacts to beat the noise problem Another use for these devises is in car fuel gauges. In a car the fuel gauge doesn't actually measure the
paper cones investigation
Investigation Report Aim Theory When an object is dropped in air, it accelerates. If it is allowed to drop far enough then it can reach its terminal velocity. This is the maximum velocity of the object during its fall and occurs when the upward force of air resistance acting on the object equals the weight of the object. So at terminal velocity... (P.31, Complete Physics, 1999, Pople, Oxford University Press, ISBN 0-19-914734-5) (P.33, Physics 1, 2000, Cambridge University Press, ISBN 0-521-78718-1) Looking for a formula for air resistance... F = force of air resistance ? = density of air = 1.2kgm-3 c = coefficient of drag for the object / dimensionless A = cross-sectional area of object hitting the air / m2 v = velocity of the object / ms-1 (http://damonrinard.com/aero/formulas.htm) Looking for a formula for the weight of an object... W = m.g W = weight / N m = mass / kg g = acceleration due to gravity, 9.81Nkg-1 (P.55, Physics, 1991, Robert Hutchings, Nelson, ISBN 0-17-438510-2) So putting these formulae together... From the Physics AS course, v = velocity x = displacement t = time so References to the specification Forces and Motion 2821 Forces, Fields and Energy 2824 Aim of your investigation The aim of this work is to investigate the relationship between the time taken for a paper cone to fall and the mass of the cone. Variables
Given a Batch of Factory Springs, Estimate the Average Spring Constant and Uncertainty of the Batch.
GIVEN A BATCH OF FACTORY SPRINGS, ESTIMATE THE AVERAGE SPRING CONSTANT AND UNCERTAINTY OF THE BATCH. Outline plan I have been given 3 springs to which I will add different weight. Using the value of extension (?x) I will calculate the spring constant. Hooke's Law says that the stretch of a spring from its rest position is linearly proportional to the applied force (stress is proportional to strain). Symbolically, F = k?x Where F stands for the applied force, x is the amount of stretch (found by new length minus original length), and k is a constant that depends on the "stiffness" of the spring, called the spring constant. Trial plan Set up equipment as above. Measure original length of spring. Add weights 0.5N at a time until spring reaches elastic limit. Record extension (?x). Plot these results on a graph and use this information to gain a sensible number and range of values to use in full experiment. Safety Notes Be sure to keep your feet out of the area in which the masses will fall if the spring breaks Be sure to clamp the stand to the lab table, or weight it with several books so that the mass does not pull it off the table. You need to hang enough mass to the end of the spring to get a measurable stretch, but too much force will permanently damage the spring, as it will have exceeded its elastic limit. Wear safety glasses to protect eyes if spring suddenly
Investigating the factors affecting the strength of an electromagnet.
Electromagnet Investigation Introduction I will be investigating the factors affecting the strength of an electromagnet. An electromagnet produces a magnetic field around the wire, it is made by passing current through a coil of wire. The strength of the field is affected by: * Number of coils * Increased current * Softer Iron core I will see if the electromagnet is more powerful when the current is increased. I will keep all of the factors of the investigation the same, to make it a fair test, this includes the same amount of coils and supply voltage. Apparatus The apparatus that I will require are: * A 2v Power Supply * An Ammeter * A Variable resistor * An Iron Bar * Wires * Crocodile clips * 100 Paper clips Method To carry out the investigation, I will first collect all apparatus and set up the circuit (as shown below). Then I will start with OA and eventually increase to 3A by altering the resistance. The current at which I will record the number of paper clips will be every 0.5 of an amp (e.g. 0 , 0.5 , 1 , 1.5 , 2 , 2.5 , 3). To make the experiment more precise and reliable, I will repeat the investigation so I have 2 results for every 0.5 of an amp, I will then make an average number. Prediction I predict that when the current is increased, the electromagnet will become more powerful, and therefore will hold more paper clips on it. To support my
How the angle of a solar cell affects its output.
How the angle of a solar cell affects its output Introduction: The aim of the experiment is to investigate the relationship between the angles of a solar cell from its light source to the output of the solar cell. I will be able to see how the relationship changes (if there is a change) by the results which I record. Apparatus: The equipment which I will require to carry out my experiment are: A solar cell A multimeter A light source These are the things which I will need to carry out the experiment but I will also need equipment make sure the experiment is accurate, these are: A clamp side with clamp, a piece of wood and blue tack, this will act as a stand on which my solar cell will be placed. The clamp stand and clamp will hold the piece of flat wood in a fixed position, to which the solar cell will be blue tacked into position, this will keep the cell firm and steady. A ruler will also be used to measure the distance of the solar cell from the light source. And a protractor will be used to measure the angle at which the solar cell is placed Diagram Safety In order to carry out this experiment in a safe way I will have to consider a few safety issues. I will have to be careful while working around the light. Because once the light has been switched on and left of a period of time the filament within the light bulb will start to heat up (because of the
Catapult Investigation
Mark Cranshaw 0P/11P Physics coursework Catapult Investigation Planning: * Preliminary work The preliminary part of my catapult investigation was to see how far I could stretch an elastic band without breaking and also to test to see what readings I could use in the final experiment. I am going to plan an experiment where I shall investigate the firing distances of 100g weights fired by two elastic bands wrapped around a stool. First of all we did our preliminary experiment. In this we investigated elastic bands to see which would be most suitable to use in our final experiment. We tested the elastic bands with different forces (1-10 Newton's) and recorded the distances of which they were stretched. I realised that if I stretched the elastic bands with more than a force of 10 Newton's then they would probably break or loose their elastic energy. Here is a diagram showing our trial experiment: The results of this experiment are shown on the graph on the next page and also below: Force (Newton's) Distance stretched (cm) 24 2 29 3 36 4 44 5 54 6 64 7 73 8 80 9 86 0 90 1 05 2 09 3 20 4 23 5 25 From the results it is quite easy to see that the bigger the force on the elastic band the further it will stretch. From this I will make a prediction: "The more force put on the elastic band the further the weight will travel the further the elastic
Investigating Electricity.
GNVQ Science Unit 1 and 3 Investigating Electricity Section A: Voltage, Current and Resistance and Ohm's Rule Firstly, to being this assignment I will be introducing what exactly Ohm's rule is and what voltage, current, and resistance is and how they are measured. * Resistance: - resistance is a measure of the degree to which an electrical component opposes the passage of current. It is the ratio of the potential difference (i.e. voltage) across an electric component (such as a resistor) to the current passing through that component: R is the resistance of the component. If the resistance of a material is low then charges can pass through it easily. (Resistance = Voltage ÷ Current) * Current: - Electric current is the rate of charge flow past a given point in an electric circuit, measured in coulombs/seconds which is named amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm's law. (Current = Number of Coulombs per second) & (Unit of current = Amps) * Voltage: - Voltage is a measure of the energy required to move a charge from one point to another. A difference in the amount of electric charge between two points creates a difference in potential energy, measured in "volts," which causes electrons to flow from an area with more
In this experiment, we investigated the relationship between the difference in work and mechanical advantage. Furthermore, we wanted to determine the difference between total work done lifting a 1kg mass up a height
The Relationship between Changes of Mechanical Advantage and Work Done Abstract (Moe Okubo) In this experiment, we investigated the relationship between the difference in work and mechanical advantage. Furthermore, we wanted to determine the difference between total work done lifting a 1kg mass up a height and dragging up a ramp as a function of mechanical advantage. We planned to change the height each times with pile-upped books and change the angles. Firstly, we measure the height of the books we piled up, the length. Then measure the angle of the ramp and we use a plank, and a spring balance to lift up and drag up the mass we repeat these steps for five times. In the result, when we changed height the work of lifting up the mass would not change but the work of dragging up the ramp would affect and we could see that when the angle of the ramp changed, work of dragging up would use more work. Also we could see that the mechanical advantage would affect too, it has getting less act when the angle of the ramp going bigger. Abstract (Eric Liu) Basically, in this lab we're going to determine the difference between total work done lifting a 1kg mass directly up a height h and dragging a 1kg mass up a ramp of length l as a function of mechanical advantage. How much easier and faster a machine makes your work is the mechanical advantage of that machine. In our experiment,
How has the Invention of Contact Lenses affected people's Sight?
Manon Mollard MP5a 14.12.04 Biology: The Impact of Man's Inventiveness on the Human Body. How has the Invention of Contact Lenses affected people's Sight? Introduction People with sight troubles have had the possibility of wearing glasses for a really long time, but the new technology made available contact lenses. In this essay, I am going to look at the different contact lenses types that exist, at who invented them and when, for which vision problems they are solution, at how to take care of them, at how common they are in our society and finally, I will write about my own opinion. What contact lenses are According to the Macmillan Dictionary (2002), contact lens may be defined as "a plastic lens that you wear in your eye to help you see more clearly". A very wide variety of contact lenses are available in today's society, including hard and soft (even if soft is by far more common now), disposable and extended wear; this makes it easy for each person to chose the appropriate type of contact lens for her. The main types of contact lenses are listed below: * Soft lenses: As these lenses are soft, they are made of a large percentage of water, and this allows oxygen to pass through the lens and reach the cornea. They are also more comfortable and easier to adapt to. * Rigid-gas
