Materials Required
- Quill tube
- Stand
- Metre scale
Real Lab Procedure
- Arrange the quill tube horizontally on a stand.
- The length of the air column is measured using a metre scale.
- Vertical heights at the two ends of mercury thread from the table are also measured using a metre scale.
- The difference between them gives the vertical height ‘h’ of the mercury thread. Here h=0. So pressure inside the tube is also H, which is the atmospheric pressure.ie; 76 cm of Hg
- The quill tube is then placed in a slanting position with the open end upwards.
- The length of the air column is measured and the vertical height, h of Mercury is noted. Now the pressure inside the tube, P=H + h.
- Quill tube is then placed in different positions, such as: vertical position with open end upwards and with open end downwards, slanting position with open end downwards and measure its corresponding length of the air column l and vertical height h.
- Now P×l is calculated in each case.
Simulator Procedure – (As performed through the Online labs)
- Use the ‘Mercury column length (cm)’ slider to change the length of the mercury column.
- Use the ‘Air column length (cm)’ slider to change the length of the air column.
- The atmospheric pressure (H) is already shown in the window.
- We can change the position of the quill tube by dragging it in different directions.
- Click on the ‘Show Scale’ button to see the 50 cm scale for taking measurements.
- We can click the arrows on the scale to rotate the scale. Also, click and drag the scale to move it to different positions.
- Now, take the readings and calculations are done as per the observation column.
- Click on the ‘Reset’ button to redo the experiment.
Observations
| Sl No. |
Position of the tube |
Height of Hg thread from table to |
Vertical height, h = h2 - h1 (cm) |
Pressure, P = H h (cm)
|
Length of air column, l (cm) |
P×l (cm2) |
| Lower end, h1 (cm) |
Upper end, h2 (cm) |
| 1 |
Vertical (open end up) |
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| 2 |
Slanting (open end up) |
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| 3 |
Horizontal |
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| 4 |
Slanting (open end down) |
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| 5 |
Vertical (open end down) |
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Calculations
- Calculate P × l in each case.
- Plot a graph between Pressure and reciprocal of length, taking pressure (P) along X axis and reciprocal length (1/l) along Y axis.
Result
From the tabular column, it is found that; P × l is a constant.
The graph between reciprocal of length and pressure is a straight line, which shows that pressure of the given mass of gas is inversely proportional to length of air column.
It indicates the inverse proportionality of pressure and volume of a given mass of gas, hence verifies Boyle’s law.
h (cm)
