# Resistance of a Wire

Jatish Patel                                Physics Investigation                                 Mr. Griffith

Physics Investigation

Resistance of a Wire

Choosing a Variable

Before I begin the investigation, I must first decide which variable I should investigate.

Variables can be divided into 2 major groups: dependant variables and independent variables. In measuring the resistance of a wire the dependant variable is resistance. This is because the resistance will change when other variables are changed.

An independent variable is a variable which cannot be affected by other variables. There are many independent variables in measuring the resistance of a wire and I must first assess which one would be a suitable one to investigate:

• Temperature- I know that temperature affects resistance; as temperature increases so does the resistance. As the atoms vibrate they make it harder for the electrons to move through the material. This is because the electrons would be obstructed by and collide with the atoms as they move. This would be an unsuitable variable to investigate because it would be it would be difficult to create an environment with a constant temperature.

• Material- The material affects the resistance; each material has a certain amount of electrons which can flow through the material which is affected by the number of electrons in their outer-most shells. If there are more electrons in the outermost shells then the resistance is lower. This variable is not suitable to investigate because results can not be plotted on a graph.

• Density- The density affects the resistance because as the atoms are much more closely packed, the electrons will collide more frequently with them. Therefore as the density increases, the resistance does so as well. This variable is not suitable to investigate because results can not be plotted on a graph.

• Length- The length of wire affects its resistance because if the wire is longer, the electrons will have more frequent collisions with the atoms. This would be a good variable to investigate because it is a very simple experiment and the results can be plotted onto a graph easily.

• Diameter- As you increase the diameter of a wire you will decrease its resistance because the electrons have more space to flow through and will have fewer collisions with atoms. This is a good variable to investigate because it is a simple procedure and the results could be plotted on a graph but we may be limited by how many different diameters we can use.

For my investigation, I will investigate how the length of a wire affects its resistance. I have chosen this variable because it is a simple variable to investigate and the results could be plotted easily onto a graph. I have chosen length as opposed to diameter because with diameter, there is a limit to how many different diameters of a wire you can use, whereas with length you can use whatever length you want.

Aim

To investigate how the length of a wire affects its resistance.

Apparatus

Metre rule-this will be used to measure the length of the wire to 2 significant figures.

Leads- these will be used to connect the length of wire to the apparatus which will be used to measure the resistance.

Length of wire- this is what we will measure the resistance of.

Masking tape- this will be used to hold the length of wire down onto the metre rule.

Ohmmeter- this will be used to measure the resistance ...