Resistance of wire

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Ruhul Amin Choudory                Physics Coursework

The Resistance of a Nichrome Wire

PLAN

Introduction

In this investigation, I shall be investigating the resistance of wire, in terms of length. But what is resistance?

The word resistance has a vast meaning in daily-use, which means to ‘oppose’, ‘forbear’, ‘withstand’, ‘avoid’ etc. (Ms Word 2003 Thesaurus). However, the term ‘resistance’ which will be used throughout this experiment is most accurately known as electrical resistance. This is basically ‘electron travelling through the wires and loads of the external circuit encounters resistance. Resistance is the hindrance to the flow of charge. For an electron, the journey from terminal to terminal is not a direct route. Rather, it is a zigzag path which results from countless collisions with fixed atoms within the conducting material’ (http://www.glenbrook.k12.il.us/gbssci/phys/Class/circuits/u9l3b.html)

The following are the factors that affect resistance:

  1. Thickness/Diameter
  2. Length
  3. Material
  4. Temperature

1) If a wire was to be thick, then obviously electrons will be able to move a little freely, but if the wire was to be thin, then electrons will move with a bit of difficulty. Since there is more space in the thick wire, therefore there is less resistance.

2) If a wire was longer than another, the longer wire will have more resistance than the shorter one due to the fact that electrons will have to travel quite a distance in the long wire.

3) Some materials of metals are better conductors than others, thus resistance is reduced. In this investigation, Nichrome wire will be used and not copper as copper is a good conductor of electricity.

4) Increase of the temperature will result in the increase of the resistance.

Aim

To investigate whether changing the length of the Nichrome wire affects the resistance.

In this experiment, the following formula triangle will be used:

V is voltage or potential difference, measured in volts

I is current, measured in amperes or amps

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R is resistance measured in ohms

Hypothesis

It is believed that ‘the longer a wire, the more resistance it will produce’. A portion of this has been explained above, but for further ideas I shall see why it is so. If we had two wires of the same kind and were investigating upon the length; and one of the wires being long as for the other being short, which wire will produce more resistance?

The long wire of course. But how?

If you were to imagine two drinking straw, both of which having same diameter but different lengths. As ...

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