Science Coursework
The Resistance of a Wire
Aim:
To find out how the length of a wire affects the resistance of it.
Knowledge:
Ohms Law is a mathematical equation that shows the relationship between Voltage, Current and Resistance in an electrical circuit. It is stated as:
, V = I x R
, R = V / I
, I = V / R
Where
· V = Voltage
· I = Current (I stands for INTENSITY)
· R = Resistance
In order to understand what Ohms Law is all about you need to understand electricity and what makes Voltage, Current and Resistance in a circuit.
Current
Current is the movement of electrons in a circuit but "What are electrons and what makes them move?"
All matter is made up of Atoms.
Piece of metal made up of Atoms
Each atom is made up of a nucleus that has a certain number of protons and neutrons with an equal numbers of electrons in orbit.
The copper atom has 29 protons in its nucleus with 29 electrons orbiting the nucleus. The electrons are arranged in orbits called shells.
Notice that in the copper atom, the outside shell has only one electron. The outer shell of any atom is called the valence shell. When the valence electron in any atom gains sufficient energy from some outside force, it can break away from the parent atom and become what is called a free electron.
It is very easy to provide enough energy to cause the valence electron to become free. Some sources of energy are heat, light, magnetic fields and a voltage source. When the valence electron becomes free it leaves behind an atom that has a positive charge. Remember that the copper atom has 29 + protons and 29 electrons so if one electron leaves orbit we are left with +29 protons and 28 electrons. That means the atom has a more positive charge because of the one less electron. This is an unbalanced atom and is not natural. The atom will always try to get an electron back into the valence orbit to become normal or balanced again.
This is the one fact that you should remember and try to visualize when working with electrical circuits.
Electric current is the movement of electrons from one atom to another in a conductor.
If you can visualize a piece of copper wire with billions of atoms and each one of them losing an electron and all the electrons jumping to other atoms, you will begin to see what current is.
An atom, by definition, is the smallest part of any substance. The atom has three main components that make it up: protons, neutrons, and electrons. Protons and neutrons are within the nucleus in the center of the atom. The electrons revolve around the nucleus in many orbitals. These orbitals consist of many different shapes, including circular, spiral, and many others.
Atoms are electrically neutral; the electrons that bear the negative charge are equal in number to the protons in the nucleus
Electricity is an interesting subject. There is so much you can learn from it, like how our lights turn on or how we make cell phones. This is all a mystery until we finally get a little bit of information in our brains. I've just read two articles, "Energy Story" and "Conducting solutions". I also watched a video called Hands-on Science with Squishy circuits. I learned so much valuable information from these resources.
The flow of electrons makes a charge that delivers useful power which could be used to light an LED
F Another wire, or exact same properties (Nickel Chrome, thickness 34). mm and length 30cm) was placed on top of the previous wire, in the same position, both straight and flat. F. The power was turned on again and the same procedure was repeated. recording current and voltage at three points on the variable. resistor.
First off, what is current. Current is expressed in a unit called Amps. Amps are a measurement of how many electrons pass per second. That is to say, a wire with 40 coulombs passing any point in a 2 seconds would be said to have 20 Amps of current (40 Coulombs (a unit of charge given as 6.24x1018 electrons) / time in seconds or in this case, 2 seconds. The Amp is also known as Coulombs per second) Another trick about current is that it is measured in the movement of the positive charge. Literally that is to say the current moves in oppostion to the electrons. This is because originally it was thought that the positive charge is what moved, both are viable, but in reality a positive charge is generally fixed since within an atom the electrons are migratory, while the protons and neutrons tend to be stationary.
The free electrons are given energy and as a result, move and collide with neighbouring. free electrons. This happens across the length of the wire and thus electricity is conducted in the building. Resistance is the result of energy lost as heat. The sand is hot.
Basic Mathematics for Electronics seventh edition: Nelson M. Cooke, Herbert F.R Adams, Peter B. Dell, T. Adair Moore; Copyright 1960
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