FACTORS AFFECTING RESISTANCE

Research Question-

How does the length of a wire affect resistance?

Through this experiment I will be investigating how the length of a wire affects resistance.

Justification-

Interaction of the charge helps us to predict electric field patterns. Resistance is a force, that is responsible for opposing the flow of an electric current. Resistance is measured in Ohms. In electronic circuits, resistors are required to adjust signal levels, reduce current flow, divide voltages and terminate the transition line models. There are several factors affecting resistance and through my experiment I aim to find out how the length of a wire (a conductor) affects the resistance of the flow of charge. In order to calculate the resistance I will divide the voltage (V ) by the electric current (I) which will give me the opposition to the flow of electric current in ohms (W).

V = W

—

I

Hypothesis –

I predict that when I increase the length of my wire, the resistance will also increase. I believe this because there will be more ions and electrons for the free electrons to collide with. So when I double the length of the wire, the resistance will double because there are twice the number of electrons and ions making it more difficult for the free electrons to travel through the wire. Therefore, I believe that the increase in resistance will be proportional to the increase in the length of the wire. This is why, the shorter the wire, the less the resistance, the longer the wire, the more the resistance.

The potential difference or the voltage across an ideal conductor is directly proportional to the current that passes through it. The constant of this proportionality is called the “resistance”, “Ohm’s Law is given by: V = I R where V is the potential difference between two points which include a resistance R.”

Variables of Investigation-

In order to ensure accuracy I will record the voltage and the current three times every and take the average results and reading.

Doing this will help in order to reduce the chance of false readings and will cancel out any false results.

I will also make sure that the wire I use for my experiment does not heat up way too much by confirming that I do not set the voltage too high and by maintaining the same the voltage for every reading I take. I will also make sure that I turn the power pack off after each reading to make sure that he temperature does not change. I will try to make this investigation as accurate as possible.

There are different variables that can be changed during the course of this experiment; these are the independent variables. However, because of my research question or my line of enquiry, I will only change the length of the wire. The variables I will control will be the type of wire (resistivity) . I will also control, using the power pack, how many volts pass through the wire. Below is a table illustrating the effect of changing the variable.

VARIABLE

WHAT

HOW WILL I…

Dependant Variable – The term dependant variable refers to what you need to measure to test your hypothesis

The dependant Variable in my experiment is the resistance of the conductor (the wire I will be using).

Measure the Dependant Variable – I will measure my dependant Variable by using a ohmmeter. An ohmmeter is an electrical instrument that is responsible for measuring resistance, which is the opposition to the flow of current.

Independent Variable – The term Independent Variable basically refers to the single factor that you are changing/comparing to test your hypothesis.

I will be changing my Independant variable at least 3 times in order to draw a line of best fit/trend line. My independent variable is the length of the conductor (the wire I will be using).

Change the independent variable – I will be changing the reaction by changing the length of my wire for every group. I will be testing this experiment using three different lengths –

5 inches of wire

10 inches of wire

15 inches of wire.

I will be changing my Independant variable at least 3 times in order to draw a line of best fit/trend line. To make sure that all my measurements are accurate I will be measuring them to two decimal places and use tested and checked voltmeter ammeters and power packs

Controlled Variable – The term controlled refers to what you need to keep the same in your experiment to be a fair test.

Temperature of the room

Why it is important to control this variable –

Since temperature is one of the factors that affects the rate of resistance, a change in the room temperature will alter and change the results of my lab drastically as there will be a change in resistance and this will keep my experiment from being a fair test. This is why it is important to keep the temperature of the room controlled

How will I control this variable –

I will be controlling the room temperature by performing the entire experiment in the same place and making sure that I do not change the air conditioning temperature.

Area of cross section

Why it is important to control this variable –

As we all know, the area of cross section in conductor is on of the factors that affects resistance or the opposition to the flow of current. As Ohm’s law states, the smaller the area of cross section, the more the resistance to the flow of the electric current.This is why a change in the cross section of the wire will alter and change the results of my lab drastically as there will be a change in resistance and this will keep my experiment from being a fair test. This is why it is important to keep the area of cross section of the conductor (the wire I will be using) controlled throughout the experiment that I will be performing.This is why it is extremely important to keep the material of the conductor of the conductor (the wire I will be using) controlled throughout the experiment that I will be performing.

How will I control this variable –

I will be controlling this factor by ensuring that the area of cross section in each of my wires remains the same so that I can ensure that my experiment is a fair test.

The material of the conductor

Why it is important to control this variable –

As we know, the material of the conductor or the wire is another factor that affects resistance on the flow of charge. Different materials of conductors have different impacts on the resistance on the flow of electric current.

How will I control this variable –

I will be controlling this factor by ensuring I use the same material for my conductor (the wire), throughout the course of my experiment so that I can ensure that my experiment is a fair test.

Diagram-

Throughout the course of my experiment, the things that I will be measuring are the voltage that will be running through the wire and the current of the wire. This will allow me to calculate the resistance of my wire. In order to calculate the resistance I will divide the voltage (V ) by the electric current (I) which will give me the opposition to the flow of electric current in ohms (W).

V = W

—

I

Apparatus-

MATERIALS

QUANTITY

Power Pack

1

Ammeter

1

Voltmeter

1

30 SWG constantan wire

35 inches

1 meter ruler

1

leads

2

Crocodile clips

4

Calculator

1

Procedure-

I will set up all my apparatus as represented in the diagram.

-Ammeter connected in series

-Voltmeter connected in parallel

2. I will make sure that the voltmeter and the ammeter are switched on

3. I will change the voltage on the power pack to two volts

4. I will record the voltage and the current

5. I will then calculate the resistance of the wire in ohms using this formula.I I will divide the voltage (V ) by the electric current (I) which will give me the opposition to the flow of electric current in ohms (W).

V = W

—

I

6. I will repeat he original test two more time, making sure that I have three accurate trials.

7. I will then calculate the mean of the result of these three trials

8. I will then repeat all these steps while calculating the resistance of the following wires

-5 inches of wire

-10 inches of wire

-15 inches of wire.

Safety Measures –

When your experiment is complete, make sure that you have cleaned up all of your work area and return all equipment to the lab supervisor.

Wash your hands before and after every experiment.