Vernier Caliper, Micrometer Caliper

Experiment 1: Errors, Uncertainties and Measurements

Laboratory Report

Denise Abril, Audrey Acosta, Jelyn Almario, Blessa Amorado

Department of Math and Physics

College of Science, University of Santo Tomas

España, Manila Philippines

Abstract

Errors are inevitable whenever measuring which leads to the uncertainty of the result. Different instruments (vernier caliper, micrometer caliper, and foot rule) were used to measure the diameter of a single sphere in order to compare their accuracy in measuring. After experimenting, it was shown that the micrometer caliper had the lowest percentage of error.

Introduction

Physics is essentially concerned with measuring the physical universe. Whenever you measure a particular object it is always against a specific standard and that gives the chance for you to commit an error. This experiment was designed to be able to study errors and how they propagate in simple experiment. It is also able to let the students be familiar with the vernier caliper, the micrometer caliper, and the foot rule for them to compare the accuracy of these measuring devices. This experiment's aim is also to compute the percent error of the three instruments through the computation of the experimental density.

Theory

The formula to calculate the deviation is

d= (∑▒x)/n (1)

Where the sum of the measurements (x) is divided by the number (n) of observations; the formula for the average deviation is then computed using the formula:

a.d.= (∑▒|x- x ̅ | )/n (2)

where ∑▒|x- x ̅ | is the sum of the absolute value of the individual deviations of the measurements divided by the number (n) of observations;

After getting the average deviation, the formula to be used to calculate the Average Deviation of the Mean is

A.D.= (a.d.)/√n (3)

where the average deviation (a.d.) previously calculated is divided by the square root of the number (n) of observations;

To calculate the experimental density of the object, the formula to be used to get the volume of the object is

V= 4/3 〖πr〗^3

where (r) is the mean diameter divided by 2;

The density is then calculated using the formula

D= m/v

where (m) is the mass and (v) is the volume;

Finally the percent error is calculated with the formula:

% error= (true value-expt.value)/(true value);

Methodology

For this experiment, the group used a vernier caliper, a micrometer caliper, a foot rule, a sphere, and an electronic gram balance.

In order to measure the diameter of the sphere using the foot rule, different points along its circumference were used.

In the case of the vernier caliper, the sphere was inserted between its jaws and the screw clamp was tightened to hold the jaws in place. The diameter was read through the use of the main scale and the vernier scale.

In the case of the micrometer caliper, the sphere was positioned by the anvil while simultaneously rotating the thimble and the ratchet knob until a click is heard; effectively locking the sphere into place between the anvil and the spindle. The diameter was read through the use of the thimble and the sleeve. The sleeve displayed the millimeters by ones while the sleeve