The Pressure Law Using ALBA Interfacing

D BurrettPhysics DepartmentHermitage 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 4Graphs 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 DataAllow 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 -320 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