The Resistance of a Wire
How does the length of a wire affect its resistance?
Aim:
The aim of this investigation is to determine how the length of a wire
can affect its resistance.
Scientific Knowledge:
Resistance means the 'opposition to the flow of current.' Electric
current is defined as the movement of free electrons; therefore
resistance is the opposition to the motion of free electrons.
Ohm's law shows the relationship between the voltage across a given
piece of metal and the current flowing through it. The law states the
following:
For a metal conductor at constant temperature, the current flowing
through it is directly proportional to the voltage across it.
It is also relevant to know of Ohm's Law, which states that the
current through a metallic conductor (e.g. wire) at a constant
temperature is proportional to the potential difference (voltage).
Therefore V ¸ I is constant. This means that the resistance of a
metallic conductor is constant providing that the temperature also
remains constant. Furthermore, the resistance of a metal increases as
its temperature increases. This is because at higher temperatures, the
particles of the conductor are moving around more quickly, thus
increasing the likelihood of collisions with the free electrons.
As voltage divided by current is resistance, this law tells us that
the resistance of a piece of metal (at constant temperature) is
constant. It can easily be shown that the resistance of a piece of
metal increases as its temperature increases.
Resistance is important because it has a controlling effect on the
amount of current which flows with an applied voltage. A resistor is
used to slow down the amount of current flowing through a circuit. If
a resistor has a small amount of resistance then it only allows a
small current through. Moreover, if a resistor has a small amount of
resistance flowing through then the resistor allows a large amount of
current to flow through the circuit. The resistance of a substance
varies with its length.
I predict that when I increase the temperature, the rate of reaction will increase. This is because when I increase the temperature I am
From this I can tell I can use 3 volts and resistance wire that is
equation V = IR. V - volts, I - current and R - resistance. I plotted
The research question asks how the solute concentration in the solution would affect the change in weight of the potato. The hypothesis posed in this lab was if the potato is placed in a 0.0M solution then it will increase in weight and if the potato is placed in a 0.2-1.0M solution then it will decrease in weight. The results yielded from the lab supported the hypothesis. When the potato is placed in a 0M solution it will increase in mass because there would be less solute in the environment, therefore making it hypotonic, causing the cell to swell up and get bigger. When the potato is placed in a solution that is 0.2-1.0M it will decrease in mass because there would be more solute in the environment, therefore making it hypertonic, causing the cell to lose water and possibly plasmolyze.
Since all metals have different densities and makeups I think that the heat capacity will greatly vary. The makeup of iron is very different than aluminum so the heat capacity will be quite different. Also, a lot of metals are not completely pure and that will also have some effect on the heat capacity.
I also decided to use a wooden block to keep hold of the wire, because
Conduction, convection and radiation are the three methods through which heat can be transferred from one place to another. The (www.hyperphysics.com) first method is the conduction through which heat can be transferred from one object to another object. This process is defined as the heat is transmitted from one to another by the interaction of the atoms and the molecules. The atoms and the molecules of the body are physically attached to each other and one part of the body is at higher temperature to the other part or the body, the heat begins to transfer. A simple experiment through which conduction can be understood easily is as follows. First of all, take a metallic rod of any length. Hold the rod in the hand or at any stand made up of the insulator so that the heat does not transfer to the stand. Heat up the one end of the rod with the help of the spirit lamp. After sometime, touch the other end of the end, the other end of the becomes heated too and the temperature of the other end of the rod has also increased. Although only one end of the rod is heated with the spirit lamp, but the other end of the rod has also been heated. This is represents that the heat has been transferred from one end of the rod to the other end of the rod without heating it from the other end. So, the transformation of the heat is taking place. This process is called the conduction. Conduction is a process which is lead by the free electrons. As the conduction happens occurs only in the metallic materials, the reason for it is that the metals has the free electrons and they can move freely from one part of the body to another part of the body. These electrons are not bounded by the nucleus so, they can move easily. And when the temperature of the ...
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.. =
Due to the interaction with air on Earth, runners experience a resistive force against the airflow. This is called the drag force, or air resistance. The equation for this drag force is given as :
of the atoms, so if there are more or larger atoms then there must be
This is know as resistivity. The factors I can investigate are : Ÿ Temperature Ÿ Length Ÿ Cross-sectional area/width Ÿ Material (resistivity) The factor I shall investigate is the length of a wire. Background Knowledge Resistance is when electrons travelling through the wire are impeded by the atoms within the wire. Since the electrons are charge carriers when they collide with the atoms in the wire less pass through.
It involves collisions between the free electrons, the fixed. particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are. carrying heat, which means that electrical energy is lost. Apparatus: I will be using an Ammeter.
V(voltage) I (current) Therefore, I = V R Therefore, if V is constant, in order to increase I, R must decrease.
Ohm’s Law is also subject to a specific amount of pressure on the substance. For example placing a conductor under tension (a form of strain), causes the length of the section of conductor under tension to increase causing the cross-sectional area to decrease, hence changing the value of resistivity and conductivity.
Toughness is the ability of a metal to mutilate plastically and to absorb energy in the process before it breaks or fracture. Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. This can be done by using heat treatment processes which include precipitation strengthening, quenching, annealing and tempering. Annealing and tempering are the most prominent methods for treating metals. A material may become more or less brittle, harder or softer, or stronger or weaker, depending on the treatment used.