• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

To investigate the factors which may affect the resistance of resistance putty.

Extracts from this document...

Introduction

Melanie Underwood                                                                                                    Physics Coursework

To investigate the factors which may affect the resistance of resistance putty

Planning

There are three different factors, which may affect the resistance of resistance putty. These three factors are temperature, length and thickness. To investigate the temperature it is very hard to make the temperature go up/down in certain intervals, it’s also hard to connect the connecting wires to the putty itself. If I were investigating the temperature, the putty would have to be placed in a water bath with a Bunsen Burner underneath. If investigating length, it is easier to connect the connecting wires to the putty whilst making sure only one variable is changed i.e. temperature has to stay the same, thickness the same, but only length changes. If investigating the thickness, the shape and length has to stay the same i.e. rounded shape at the end or square, but only the thickness changes. The thickness could either be measured by measuring the circumference or diameter of the end.

For my investigation, I am going to investigate the length factor to see if the resistance of resistance putty changes. This is because it is the easiest factor to change just one variable, whereas with the others it is slightly harder to change just the one variable.

I predict that for my experiment, the longer the length is, the greater the total resistance will be. I predict this because when doing a previous experiment with changing one variable (length) of a piece of resistance wire in a circuit, the total of resistance increased as the wire got longer. This is because when using a rheostat, the current has to flow through a longer length of coil and we see that the current is smaller, showing the resistance is larger.

...read more.

Middle

1  + 1 ….

R total     R     R     R

For my experiment I need to make it as fair a test as possible. To try to do this, only one variable will be changed (length, not the width nor temperature). Therefore, the width of the resistance putty has to be checked regularly to make sure that it is the same throughout. The temperature also has to stay the same, this can be done by keeping the voltage low so that the putty doesn’t heat up. The rest of the circuit which is going to be used also needs to stay the same, this involves being careful when disconnecting the resistance putty from the circuit and replacing the resistance putty back in.

The apparatus which is going to be needed/used, are 3 cells, ammeter, voltmeter, crocodile clips x 2, scalpel, coins x 2, resistance putty, connecting wires, pair of plastic gloves, and a tray lined with plastic. Some of this apparatus is used to keep ourselves/area clean, the others are to be set up in the circuit as shown.image16.pngimage03.pngimage03.pngimage16.png

image03.pngimage23.pngimage04.pngimage02.pngimage05.png

image07.pngimage06.png

image10.pngimage03.pngimage08.pngimage03.pngimage03.png

image12.pngimage12.pngimage11.png

image16.pngimage15.pngimage14.pngimage13.pngimage17.pngimage18.pngimage20.png

image21.png

The two coins are pressed into the putty at either end, then the crocodile clips attached to the coins. This is to prevent the error of changing another variable (width) by accident.

The range to be used is going to be from 20cm to 6cm and in intervals of 2cm each time. This results in taking 8 readings all together.

To ensure the experiment is carried out safely, the scalpel (which is used to cut the resistance putty) will only be held when it is needed, otherwise it remains on the bench. The experiment is not going to

...read more.

Conclusion

There is also only one point on the graph, which is away from the best-fit line. This could be because I was not being accurate enough with having exactly 8cm of resistance putty and having the width exactly the same as with all the other different lengths. It could also be because for this length, there wasn’t such a good connection to the putty from the circuit or the current was not accurate enough. This could be due to the readings constantly fluctuating and the current reading being too small.

Despite having nearly one anomalous result and one point on the graph not on the best-fit line, I think I can say my conclusion is more likely to be valid than invalid. Unless it was just by chance that only one point on my graph didn’t fir on the best-fit line.

To make my conclusion more valid, more experiments could be done. If I had more time, I would have investigated these too, so I could get a more valid conclusion.

These experiments would still involve changing just one variable, but instead of having a constant width of 2cm in diameter, the constant width could be 5cm in diameter instead. Or, instead of having a constant temperature of 15°C, a constant temperature of 20°C could be used whilst only varying the length. Even though different resistance values could be calculated, the graph drawn should resemble the same shape as that of the other graphs where only the length is varied for a piece of resistance putty. If this does happen, then it can be safely concluded that my conclusion and results were accurate. But until then it is very difficult to tell whether they are or not.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Electrical & Thermal Physics essays

  1. Marked by a teacher

    Internal Resistance of a cell

    5 star(s)

    Graphing the results gained after the experiment of new and old battery 5) Identified the gradient and the y- intercept of the best fit line for each set of the data And for the values of the currents (independent variables)

  2. Investigating the E.m.f and Internal Resistance of 2 cells on different circuit Structures.

    Voltage (2nd attempt) Current (mA) (1st attempt) Current (mA) (2nd attempt) 12 15 18 22 33 47 68 100 120 150 180 220 1.35 1.36 1.37 1.38 1.40 1.41 1.42 1.42 1.42 1.43 1.43 1.43 1.34 1.36 1.37 1.38 1.40 1.41 1.42 1.42 1.42 1.43 1.43 1.43 .113 .090 .077 .063 .042 .029 .018 .013 .011 .009

  1. Does the length of a conduction putty affect its resistance?

    am investigating is an Ohmic conductor, as even when the potential difference changes, the resistance of the putty remains constant for the same length. Now that I have proved that the putty does conduct electricity in a constant manner, I can start the main experiment.

  2. Practical Assessment for Physics: Investigating the Resistance of Conducting Putty.

    With my results I created an average voltage reading for each length of putty by adding their ten readings and dividing it by ten. I also did the same to create an average of the current for each length of putty.

  1. Investigating how temperature affects the resistance in a wire

    To combat this problem, the experiment was conducted at room temperature, which means that there would not have been any significant changes in room temperatures. Heat from other sources can also directly affect the temperature of the water bath, so to combat this problem it is kept constant with the

  2. To investigate how the temperature affects the resistance of a thermistor.

    was in one of the results record I could have taken down the resistance at a higher temperature than it should have been which would therefore affect the average. In which case, the anomaly is due to carelessness and inaccuracy.

  1. Investigating the effect of 'length' on the resistance of a wire

    A variable resistor consists of a conducting track of resistance material with a fixed contact at one end and a sliding contact on the track. Moving the contact along the track changes the length of material and also the resistance between the contacts.

  2. I am going to investigate what the resistivity is of a pencil lead. ...

    I will try to make it as accurate as possible by using an electric ammeter and a voltmeter where the intervals are 0.1V. Preliminary Experiment I will be carrying out a preliminary experiment so that I know exactly what I am doing and can eliminate any problems that I may come across.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work