Monday, April 8, 2019
This coursework assignment is to investigate resistance Essay Example for Free
This coursework assignment is to investigate justification EssayTo investigate it, we must first understand it. What is it? Where does it come from? The most fundamental basis to understand resistance is to know about modern. Electric current is a flow of electric automobile charges. Like water supply supply in a heating system, the charged particles atomic number 18 already in the film directors. Most electrons in a conductor (e. g. copper) are held tightly to their atoms, but each atom in a conductor has a couple of electrons that are loosely held.Since the electrons are negatively charged, an atom that loses an electron is left with a arbitrary charge (since the protons remain), and is called an ion. This means that copper (and all similar conductors) consist of a lattice of ions surrounded by issue electrons. The ions can only vibrate in their current state, but the electrons can keep helter-skelter throughout the lattice. All metals (conductors) are made this w ay. When a battery is attached to a metal, the free electrons are repelled by the negative terminal and attracted by the positive one.They still move randomly, but they all move slowly in the similar direction with a steady drift velocity. This is a flow of charge, an electric current. Current is thrifty in Amps (I). A simple circuit through a conductor looks desire this The greater the resistance of a component, the harder it is for charge to flow through it. In a conductor with a higher resistance, the electrons turn in more(prenominal) collisions with the ions than if they were flowing through a conductor with dismantle resistance. If there is a potential difference (Voltage, V) crossways a conductor, a current (Amps, I) goes through it.But when you apply the alike(p) potential difference crossways different conductors, the currents are different. For example, if we put a potential difference of 230V across a kettle and toaster, the current in the kettle is 10A, whereas the current in the toaster is only 5A. The current is smaller in the toaster so it must have a higher resistance. Resistance is measured in ohms (? ) and has this definition The resistance of a conductor is the ratio of potential difference applied across it, to the current passing through it So the formula for resistance is Resistance, R = Potential difference across the conductor, V (volts)(? ) Current through the conductor, I (amps) or R = V or V = I R I As the potential difference doubles, so does the current. This means the resistance of a telegram is constant. This rule was discovered by Georg Ohm and is true for all metals at a constant temperature. As spacious as a metal is kept at a constant temperature, the current through a conductor is directly proportional to the potential difference across it This is ohms law, and it can help us to make it good results. There are a number of factors affecting how much resistance a conductor has. They are theseType of substantive D ifferent conductors have different levels of resistivity. E. g. Copper has a much lower resistance than nichrome. Length A short wire has less resistance than a long one. The free electrons have to travel a farther distance in the long wire, passing between more ions. This increases the chances of an electron hitting one, therefore there are more collisions, thus a higher resistance. cross-section(a) area A thin wire has more resistance than a thick one. This is simple overdue to the fact that more electrons can flow through a thicker wire, similar to the way more water can pass through a wider pipe.Temperature In metals, a hot wire has more resistance than a cold one. This is because, as a metal heats up, the ions vibrate more. This increases the chance of them colliding with electrons, thus there is a higher resistance. The resistance of a wire at constant temperature depends on its dimensions, and the material from which it is made. Every material has a property called its re sistivity (p). It is measured in ohm metres (? m). The higher the resistivity, the harder it is to charge flow through the material. Conductors have low resistivities and insulators have very high ones.If we know the resistivity, the cross-sectional area and the length of a specimen material, we can calculate its resistance thus Resistance, R = Resistivity, p (? m) x length, l (m) or R = p l (? ) Cross-sectional area, A (m2) A So now that we understand what resistance what are we going to do with it? Why an experiment of course Im going to be investigating how the length of a wire affects the resistance. I will try passing the same voltage through different lengths of the same wire and see how length affects the resistivity. Prediction I predict that the longer the wire is, the higher the resistance.