Determining the diameter of a piece of Nichrome wire by determining its resistivity

Authors Avatar by pahuadignity123gmailcom (student)

Candidate Name:                

Session: May 2015                 Page |

International Baccalaureate Diploma Program (IBDP)

Session: May 2015

Physics HL Lab Report

Lab Report Title: Determining diameter using resistivity.

Criteria Assessed:

  • Data Collection and Processing (DCP)
  • Conclusion and Evaluation (CE)

Candidate Name:

Candidate Number:

International School, Singapore

AIM: To determining the diameter of a piece of Nichrome wire by determining its resistivity.


Metals have low resistance due to their delocalized field of electrons. However, different metals have different values of resistance. In this experiment, the students were given a spool of Nichrome wire to determine its diameter. Nichrome, as the name suggests, is an alloy of Nickel, Chromium and Iron.

The resistance of a conductor depends on its inherent resistivity (ρ), length (l) and its cross-sectional area (A). The resistance is given by the following formula (#1): . Where,

R = Resistance (Ω)

ρ = Resistivity (Ω.m)

l = length (m) and,

A = cross-sectional area of the conductor.

To determine the cross-sectional area of the wire, the diameter was first determined using a micrometer screw gauge. The formula (#2) that relates the diameter to the cross sectional area of the wire is:

The electrical resistance can be determined by an ohmmeterlength, using a ruler, and the resistivity was determined by the literature value of 1.25×10-6 Ω.m. 

Substituting the literature value for Nichrome’s resistivity () and formula #2 into formula #1, the following equation can be obtained:  This equation can graphically represented by l on the y-axis and R on the x-axis. The gradient would then give the value for which could then be manipulated to extract the value of d.

Join now!


Independent Variables:

  1. Length of the wire used. (l)

Dependent Variables:

  1. Resistance of the circuit. (Ω)

Controlled Variables:

  1. Voltage of the circuit. (V) – The same power source was used for all trials of the experiment.
  2. Texture of the Nichrome wire. – It was wiped clean of any contaminants such as oxides etc.
  3. The measuring tape – The same measuring tape was used to measure all heights.


A simple circuit was set up with the Nichrome wire as the ...

This is a preview of the whole essay