Physics Resistivity of a Wire
AIM- OUR AIM WAS TO FIND OUT WHICH VARIABLES AFFECT RESISTANCE, AND WHICH ONE HAS THE GREATEST EFFECT.
BACKGROUND INFORMATION:
Resistance is the force that opposes the flow of electrons in a circuit. The equation for resistance is Ω=V/A. (Ohms equals Voltage divided by amps).
Resistivity is a measure of how strongly a material opposes the flow of electrical current,
There are four main factors that affect resistance:
Length – this is because the electrons would bump into more atoms, the longer the wire which is like using up its fuel.
Material – different materials inherent resistances as they have more or less atoms in them already.
Thickness – Thickness affects resistance because the thicker the wire the more paths the electrons have to avoid the atoms. Therefore the cross sectional area is larger so there is less resistance.
Temperature – The hotter the wire is the more energy the electrons have to flow faster.
Why do we get resistance? An electric current flows when electrons move through a conductor. The electrons collide with atoms of the conductor causing resistance as this makes it harder for the current to flow. Electrons collide more often in a long wire than they do in a short wire. A thin wire carries fewer electrons so the resistance is lower. This means the resistance of a wire increases as:
-The length of the wire increases
-The thickness of the wire decreases
The diagram below shows the collision between electrons and atoms in a wire.
Pilot Experiment 1/3: Nichrome
In order to test resistivity, we took measurements of the same metal by running an electric current through it. After completing the circuit, it was then possible to read the voltage and current from the voltmeter and ammeter. The idea of the experiment was to test the resistivity of a metal with varying lengths. For our first pilot experiment, we measured the resistivity of a Nichrome wire; I did this experiment to see whether the length of a wire affects resisitivity.
BACKGROUND INFORMATION:
Resistance is the force that opposes the flow of electrons in a circuit. The equation for resistance is Ω=V/A. (Ohms equals Voltage divided by amps).
Resistivity is a measure of how strongly a material opposes the flow of electrical current,
There are four main factors that affect resistance:
Length – this is because the electrons would bump into more atoms, the longer the wire which is like using up its fuel.
Material – different materials inherent resistances as they have more or less atoms in them already.
Thickness – Thickness affects resistance because the thicker the wire the more paths the electrons have to avoid the atoms. Therefore the cross sectional area is larger so there is less resistance.
Temperature – The hotter the wire is the more energy the electrons have to flow faster.
Why do we get resistance? An electric current flows when electrons move through a conductor. The electrons collide with atoms of the conductor causing resistance as this makes it harder for the current to flow. Electrons collide more often in a long wire than they do in a short wire. A thin wire carries fewer electrons so the resistance is lower. This means the resistance of a wire increases as:
-The length of the wire increases
-The thickness of the wire decreases
The diagram below shows the collision between electrons and atoms in a wire.
Pilot Experiment 1/3: Nichrome
In order to test resistivity, we took measurements of the same metal by running an electric current through it. After completing the circuit, it was then possible to read the voltage and current from the voltmeter and ammeter. The idea of the experiment was to test the resistivity of a metal with varying lengths. For our first pilot experiment, we measured the resistivity of a Nichrome wire; I did this experiment to see whether the length of a wire affects resisitivity.