The Pressure Law Using ALBA Interfacing D Burrett Physics Department Hermitage Academy Argyll & Bute

Apparatus ALBA temperature sensor ALBA pressure sensor ALBA interface Round bottomed flask (fully immersed, with hose to pressure sensor) Kettle

Setting Up ALBA Interface Connect power lead to mains supply Connect communication lead to PC Connect ALBA temperature sensor (analogue ch3) Connect ALBA pressure sensor (analogue ch4)

Setting Up ALBA Investigator 1 Start ALBA software Select ‘Run the Investigator’ from Startup menu

In General Settings select – –10 s logging interval –Both Graph & Table Setting Up ALBA Investigator 2

Setting Up ALBA Investigator 3 In ‘Channels’ Settings ensure – –Temperature sensor is detected on Analogue input 3 –Pressure sensor is detected on Analogue input 4 No other settings need to be changed, click ‘OK’ to continue.

Setting Up ALBA Investigator 4 Graphs and table should appear in back ground behind ‘Setup Table Headings’ Box. Change Channel 3 to ‘Temperature’, symbol ‘T’ Change Channel 4 to ‘Pressure’, symbol ‘p’ Click ‘OK’, then ‘Go’ to begin experiment.

Collecting Data Allow experiment to run until water in kettle boils.

Data Analysis 1 Close both graphs Click ‘Time’ column in results table Select ‘Table’ menu, then ‘Remove Column(s)’ and confirm Click ‘Use Data Points’ column Select ‘Table’ menu, then ‘Add Column(s)’ choose ‘1’ new column

Data Analysis 2 Double click on table heading, change column properties Click on ‘Table Column Calculator; button

Data Analysis 3 Type formula into calculator and confirm Click ‘Temperature’ and ‘Tot Pressure’ table headings Click ‘Quick Graph’ button Expand graph

Data Analysis 4 Double click on entries in ‘Use Data Points’ column to de-select data and remove ‘plateau’ from graph Select ‘Graph’ menu, ‘Tools’ then ‘Best-fit line’

Data Analysis 5 Select ‘Graph’ menu, ‘Edit graph’ De-select ‘Auto- scale’ Set x-axis from to 100, y-axis from 0 to 120 Click ‘Apply’

Data Analysis 6 To find intercept on x-axis, place mouse pointer over graph Value of intercept appears at top left corner of graph

Evaluation 1 True value of absolute zero is -273°C Experimental value is too low because – –Temperature measured by ALBA is not temperature of gas in flask – it is water temperature –Pressure sensor is subject to a systematic error, under-reading by a small amount.

Evaluation 2 Possible improvements –Place temperature sensor inside flask –Quantify systematic under-reading of pressure sensor and adjust pressure readings accordingly in data analysis –Encourage ALBA developers to produce a stand alone ALBA application for the pressure law