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.
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.
An electrode is a component of an electric circuit that connects the conventional wiring of the circuit to a conducting medium such as an electrolyte or a gas. The electrically positive electrode is called the anode and the negative electrode the cathode. If an anode and a cathode are placed in a solution of an electrolyte and a source of direct current is connected between them, the positive ions in the
Metals contain a sea of electrons (which are negatively charged) and which flow throughout the metal. This is what allows electric current to flow so well in all metals. An electrode is a component of an electric circuit that connects the wiring of the circuit to a gas or electrolyte. A compound that conducts in a solution is called an electrolyte. The electrically positive electrode is called the anode and the negative electrode the cathode.
The flow of electrons makes a charge that delivers useful power which could be used to light an LED
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.
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.
E_cell^o was determined to be 0 V since the same metal was used as the electrodes. In doing so, the differences in the standard reduction potentials was 0 V. The R value, the ideal gas constant is given in 8.314 J/(mol K), T is the temperature at standard conditions (298.15 K), n is the number of electrons transferred (2 in this case), and F is the Faraday Constant of 96485.3399 J/(V mol). The reaction quotient, Q, was determined to equal the concentration of the concentrated Copper ion divided by the diluted Copper ion concentration (Q=([Cu_diluted^(2+)])/([Cu_concentrated^(2+)])= .05 M). The average corrected Ecell was found to be .042 V, givng a 10.52% error when compared to the theoretical
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
For a second, imagine yourself in a frozen cabin, with wet wood, oil and wax, trying for hours to make a fire in order to get light and heat in your room. This procedure ended in 1897, thanks to the American inventor Thomas Edison, who was finally able to produce a long-lasting light-bulb in his laboratory. Although it looks simple that turning on the lights just require to turn the switch on, the scientific theory behind it is quite complicated. Creating an electrical system requires a conversion from any sort of energy to electrical energy. For example, one of the first electrical energy sources was coal. Burning coal produces high temperatures that transfer into potential energy. Potential energy is then changed to electrical by the application of stress.
The invisible bits of negatively charged matter that move between objects are called electrons. The words electron, electricity, and electronics all come from the Greek word for amber – elektron. The transfer of electrons explains the electric force that attracts the balloon to the wool. Rubbing the neutral balloon with the wool cloth allows some electrons to leave the wool and stick to the balloon.
To start off, learning the Bohr-Rutherford diagrams in grade nine was a very big confusion for me. I had never fully understood how many shells should go around the nucleus nor did I know how to do the many calculations. As I progressed into grade ten, the teachings became easier. The review shows an example such as in the the bohr diagram, a nucleus is in the center, which is a little circle, and following that there are shells surrounding it containing electrons. Each ring can only hold a certain amount of electrons, and so the first shell around the nucleus can hold a maximum of 2 electrons, the next shell is able to hold a maximum of 8 electro...
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 phenomenon called electromagnetic induction was first noticed and investigated by Michael Faraday, in 1831. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is a very important concept. Faraday discovered that, whenever the magnetic field about an electromagnet was made to grow and collapse by closing and opening the electric circuit of which it was a part, an electric current could be detected in a separate conductor nearby. Faraday also investigated the possibility that a current could be produced by a magnetic field being placed near a coiled wire. Just placing the magnet near the wire could not produce a current. Faraday discovered that a current could be produced in this situation only if the magnet had some velocity. The magnet could be moved in either a positive or negative direction but had to be in motion to produce any current in the wire. The current in the coil is called an induced current, because the current is brought about (or “induced”) by a changing magnetic field (Cutnell and Johnson 705). The induced current is sustained by an emf. Since a source of emf is always needed to produce a current, the coil itself behaves as if it were a source of emf. The emf is known as an induced emf. Thus, a changing magnetic field induces an emf in the coil, and the emf leads to an induced current (705). He also found that moving a conductor near a stationary permanent magnet caused a current to flow in the wire as long as it was moving as in the magnet and coiled wire set-up.