Resistance of a Wire
I have been asked to solve the problem of getting a resistance of 1.9
ohms using resistance wire. Resistance is how easily a potential
difference is carried across a conductor. The higher the resistance,
the bigger the potential difference has to be to go through the
conductor. To do and understand this investigation I must see firstly
what factors are involved when looking at resistance. I have come up
with six things which affect the resistance in a wire:-
Thickness-
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If the wire is very thick i.e. it has a big cross sectional area
(csa). It will have a smaller resistance than one with a smaller csa.
This is because electric current in a metal is made up of electrons
jumping and hitting more electrons, like dominoes. The metal ions in
the wire block some electrons, causing a resistance. If there is a
bigger area through which the electrons have to squeeze, the
resistance will evidently be lower.
Material of Wire-
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This is quite an obvious one, as I know that all materials have
different conductivity. For example copper is a better conductor than
tungsten but silver is the best. By knowing what the conductivity of a
material is, I know how much resistance it would have, as the better
the conductor the less the resistance.
Temperature-
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As temperature increases so does resistance. If a wire has a high
temperature, then the ions in the wire will be vibrating more. This
means there are more collisions between the ions and the electrons
trying to get past. This would result in a greater resistance. It
could be likened to a packed corridor in a school. If you are going
one way, and everyone else is going the other, it is easier to get
past them if they are still and not moving.
Length of Wire-
As the length of the wire increases, the resistance should increase
too. This is because since there is more length, there would be more
I also decided to use a wooden block to keep hold of the wire, because
longer it will take electrons to get to the end of the wire. This is
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
have to be across the wire and not just anywhere in the circuit so it
there will be. So if the length of the wire were to double, so would
V is voltage in volts and I is current in amperes. L:- is the length
50cm for us. The current will be kept on the same level using the same
Investigating the Resistance of a Wire The aim of this investigation is to see how the length of a wire affects its resistance. Background knowledge To make current flow through a conductor, there must be a potential difference (voltage) across it. As the current continues to flow there are certain factors which increase the resistance; Length of wire: as the length increases there will be a higher percentage of fixed atoms, therefore the electrons carrying the charge will collide more frequently, increasing the resistance Surface Area of wire- As you increase the surface area of a wire the resistance will decrease because the electrons will be able to travel by many different routes making the conduction easier. Type of conductor- If the wire is a good conductor of electricity then the resistance will be less because the electrons are able to flow through the wire avoiding as many collisions with the positive protons.
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.
Factors Affecting the Resistance of a Wire The aim of this experiment is to investigate one factor that affect the resistance of a wire. I will do this by performing an experiment. First I will need to identify the factors that effect resistance. There are a few factors that affect the resistance, it is determined by the properties an object has.
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.. =
Investigating the Resistance of a Wire We have been given the task to investigate the resistance of different wires, I am firstly going to start by explaining what resistance is, why it occurs, what causes it, and how it can be used to our advantages. Resistance is a term used to describe the property that various materials possess to restrict or inhibit the flow of electricity. Whether or not a material obeys Ohm's law, its resistance can be described in terms of its resistivity. The electrical resistance of a wire would be expected to be greater for a longer wire, less for a wire of larger cross sectional area, and would be expected to depend upon the material out of which the wire is made.
of the atoms, so if there are more or larger atoms then there must be
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.