Investigating the resistance of resistance wire

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David Swiggs

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Investigating the resistance of resistance wire

Problem:  “Investigate one of the factors that effects the resistance of resistance wire”

Normal wire is used for conducting electricity; the best wire is the one that gives out the same amount of electricity that was put in. The wire is made out of copper because it is a good conductor of electricity. Resistance wire is used in appliances like dimmer switches. You can control how much electricity out of the end of the wire.

    Current is the movement of electrons through a structure that conducts electricity. These electrons are said to be delocalised.

                                                                                                           Metal ions in an      

                                                                                                           ordered lattice

                                                                                               Localised electron clouds

                                                                                         associated with one particular

                                                                                          nucleus

                  Delocalised ‘mobile’ electrons

Delocalised electrons are the ones that move in metals when electricity is passed through them. An alloy is two or more metals chemically combined. Resistance wire is made from nichrome; it is an alloy of nickel and chromium. In alloys the delocalised electrons are either blocked or moped up.

Factors

The factors that I think will affect the resistance of resistance wire are

  • Length
  • Diameter
  • Temperature
  • Material
  • Condition of the wire
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From the ‘physics for you’ textbook, page 254, I found out the following statements:

‘As the length increases, the resistance increases, as cross-sectional area increases, the resistance decreases, as temperature increases, the resistance of wire increases’.

I also believe that the material will alter the resistance but by how much is unpredictable.

Plan

  1. Make sure the equipment works.
  2. Set up equipment as show in circuit diagrams - Make sure ammeter is connected in series and voltmeter is connected in parallel.
  3. Turn on power source
  4. Connect voltmeter, one end at 0cm and the other at 100cm
  5. ...

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