Experiment on Electrical Resistance
The electrical resistance of a material is its opposition to the flow
of electric current (slowing the flow of electrons down). Resistance
occurs when the electrons travelling along the wire collide with the
atoms of the wire. These collisions slow down the flow of electrons
causing resistance. Resistance is a measure of how hard it is to move
the electrons through the wire.
A current is the rate of the flow of charge (electrons) and the
resistance controls the amount of current flowing. If we want to
calculate the current flowing through the circuit, we need to know how
much resistance it has. A resistor that has a large resistance only
allows a small current through it and a small resistance allows a
large current through. Resistors are usually long coils of wire, or
small pieces of material that do not conduct electricity very well,
therefore the conductivity of the metals affect resistance. As the
potential difference (voltage) between the ends of conductor is
increased the current passing through it increases. If the temperature
of the conductor doesn't change, the current that flows is
proportional to the voltage applied. This is called Ohms Law.
Ohms Law= Potential Difference x Current or
Potential Difference = resistance x current or
The unit of resistance is measured in Ohms (W).
Measuring Resistance
The voltage across the resistor is measured using the voltmeter. The
current flowing through the resistor is measured using the ammeter.
The resistance can then be calculated using the formula: Resistance =
Voltage
Current
The width, length, material and temperature are factors, which affect
the resistance of a wire.
Temperature: If the wire is heated up the atoms in the wire will start
to vibrate because of their increase in energy. This causes more
collisions between the electrons and the atoms as the atoms are moving
into the path of the electrons. This increase in collisions means that
there will be an increase in resistance.
Material: The type of material will affect the amount of free
The behavior of every material composite substance is either completely deterministically caused by the nature of the material parts making it up or is partially randomly caused.
I intend to change the volume of the copper sulphate I shall change this by going up 10cm3 each time. To keep my experiment safe I shall wear goggles and have a bench wipe close by to mop up any spillages. I predict that when the volume of copper sulphate is increased the current going though it will also increase, and if the volume is doubled the current should also be doubled. I believe my prediction to be true and I will now try to prove this by using my scientific knowledge and other resources.
The first term that I noted during the movie was Conductive Polymers. Conductive polymers are almost always organic meaning a large class of chemical compounds whose molecules contain carbon. These polymers have extended delocalized bonds which are bonds found in a molecule that do not belong to a single atom or covalent bond. They are conjugated systems of double bonds and in a aromatic systems. The conjugated systems are atoms covalently bonded with alternating single and double bonds. When the electrons are removed or added into the valence bands the electrical conductivity increases. The conductive polymer has a low conductivity until the electron is removed from the valence band called (p-doping) or (n-doping) until it becomes more conductive. The movement of the charges is what is responsible for electrical conductivity. These polymers are plastic which are organic polymers and with mechanical properties such as flexibility and elasticity.
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.
equation V = IR. V - volts, I - current and R - resistance. I plotted
I also decided to use a wooden block to keep hold of the wire, because
Investigating the Effect the Thickness of a Wire has on Its Resistance. Equipment:.. Nickel Wire cut into 10 pieces of 30cm length (Ruler, Pliers). Two crocodile clips Five Pieces of Wire Power Source Variable Resistor Ammeter Volt Meter Method: The.. =
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There fore less current passes through with the same voltage. Simply it is how hard it is for the electrons to pass through the wire. Temperature: When the metal wire is heated , more energy s given to the atoms, therefore they vibrate more. From this there is a greater chance of collisions with the electrons and they are impeded more, therefore less charge is passed by the electrons and the resulting current is reduced. This means while conducting the experiment the temperature of the wire must be kept constant to maintain a safe and fair test.
In the experiment there are several possible ways of changing the electric current such as changing the voltage or the position of the electrodes within the electrolysis cell. However, it was found from preliminary work that the most effective way to change the current was to change the concentration of the acid solution. The preliminary work showed that the greater the concentration of the acid, the greater the current. Ohm's law states that R(resistance) =
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There are formulas to calculate electrical conductivity and resistivity. Conductivity (s) is defined as the inverse of resistivity (a high conductivity means a low resistance), I=V/R or current equals voltage over resistance. Electrical resistance is calculated by the formula, R=V/I or resistance equals voltage over current.
Most materials fall into two categories: conductors and insulators. These materials conduct or do not conduct electricity, respectively. Now, how well this electricity can flow through a conductor is a measure known as resistance. Electricity flows by raising electrons from a lower energy level to a higher energy level in the atoms of ...