# Sensors Project Report

Contents

1. Aim                                                                 P.2

2. Alternative ways that experiment                                  P.2

3. Plan                                                                                      P.3

4. Variables                                                                                         P.3

5. Precautions                                                                           P.3

6. Preliminary results and Prediction                      P.4

7. Apparatus                                                                     P.5

8. Diagram of the Circuit                               P.5

9. How does a potential divide work?                     P.5

10. Table of results                                                         P.6

11. Calibration Curve – Average Results                   P.8

12. Reliability and Accuracy                             P.10

13. Sensitivity                                               P.10

14. Resolution                                               P.11

15. The error of the experiment                          P.12

16. Improvement of the experiment                       P.12

17. Fitness for the purpose                                            P.12

18. Sources                P.13

Sensors Project Report

Preliminary planning

Aim

To measure the number of papers in a pile by creating a very sensitive sensor with the use of resistors

Alternative ways that experiment can be set up

• Using infra-red sensor by passing through infra- red and determines the thickness of paper and the number of sheets by detecting the amount of infra- red passing through. However, that does not work due to the limitation of equipment
• Using a balance and determine the number of sheets of paper by mass, but that would not be very accurate due to the fact that the mass of every pieces of paper might vary and the balance is not very sensitive to a tiny amount of change (e.g. only 1 piece of paper is put on)
• Using a calliper to determine the thickness of one paper and then determine the number of papers there are by dividing the thickness of the pile of paper by thickness of one piece of paper. It is not very accurate because the thickness of paper varies from one side of the paper to another and from one piece of paper to the other.
• Using a log Potentiometer to determine the number of sheets of paper in the sensor by the thickness of the paper (number of papers) and that varies the ratio of the resistance in the potentiometer so the number of papers can be determined by the ratio.

From all the choices above, the potentiometer is chosen because it is more related to the work in the syllabus and it is one of the most accurate ways to measure among the others that have been suggested. To make the sensor more sensitive, another variable resistor is used to allow it to become more sensitive. The physics will be explained afterwards as a potential divider.

Plan

1. Set up the circuit with two variable resisters, three 1.5V batteries, a multimeter (set up to measure the voltage, in volts).
2. The circuit will be set ...