An Investigation To See How Resistance Can Be Changed By Variables.

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David Anthony

An Investigation To See How Resistance Can Be Changed By Variables.

Background Information;

In order for the resistance to be changed I need to know the variables. To keep the current constant using an ammeter and variable resistor you will insure that you are not changing a constant. Copper wire will be used to link up the circuit this gives such little resistance that it is normally regarded as having no resistance. I think I will use size 24 wire as it is not to small and will not burn (giving an odd result) and not to big that so the resistance is not to high.

Three wires that are available are Copper, Nicrome and Constanton. The highest resistance should give me greater variance at the extremes so it is easier to record. In a pre-test I shall find out which wire has the highest resistance, before I decide which one to use. The only problem with using the highest resistance is that if temperature is increased so will the resistances, so voltage will have to be low enough to not effect results.

Variables;

Wire Type- there are three types of wires Copper, Nicrome and Constanton. I will be using Constant as it gave the best range with out compromise of heat or length.

Wire Length- the longer the wire the greater the resistance. I will be changing the variable wire length between a range.

Cross Sectional Area- this is proportional to resistant and length so will not effect results.

Current- this will be kept low so will not become hot, and effect resistance. A set value will be decided.

Temperature-the higher the temperature the wire is at the more resistant it becomes and will be cheap low enough not to let the temperature increase.

Equtions;

      R = V

              I            Resistance is equal to Voltage/Current

                                                                                    R         L            

C.S.A

Circuit;

Outline Plan;

  • The variable I will be changing is “length of Constanton wire.”
  • I will find the length in a pre-test. I will also combine the to together to find out the range of length with the wire type.
  • I prepare the equipment setting out the circuit as shown and always making sure the amp. Meter reads 0.1 amps, to a nearest decimal place. To obtain this can be done by moving the variable amp. Meter as it is making sure the content is constant as the resister is not a value if the amp. Meter reads 0.1amps.
  • Check the wire for short circuits, turning on power if there is no wires touching.
  • Ensure voltage is low enough for the amp. Meter to read 0.1 amps.
  • Take results moving the length and repeating evaluate data collect any more data if there is any anomalous and needs checking out.
  • Pack up equipment.
  • Analysis and the resulting data conclusion including graphs.
  • Evaluating data- showing strengths and weaknesses of the plan and data collected.

Plan;

To measure the distance of the wire, I will measure going in ten centimetres from ten to ninety. I will be using a meter stick and carefully stuck the wire to it. This insured that the same wire is used and measured in the same way if I have to collect data on anther day.

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  • Step one- ensure power supply is not on when putting socket into switch.
  • Step two- set the wire and the measuring stick up using masking tape to attach it.
  • Step three- set up the circuit making sure all the connections are together and no wire is crossing.
  • Step four- making sure power pack is on a low voltage and switched on take readings.
  • Step five- ensure meter is reading out 0.1 amps. when taking results make sue they are not silly or look out of place.
  • Step six- repeat steps before until all data is collected,
  • Step ...

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This is a well structured and well written report. 1. There is a running commentary in this report that needs to be removed. 2. The sources of information need to be referenced. 3. The conclusion needs to include data to back up the patterns. 4. The evaluation should suggest further research opportunities. ****