Page 102 - Physics - XI

Mechanical Properties
6 Mechanical Properties
of Fluids
of Fluids

EXPERIMENT - 3

Aim
To study the variation in volume with pressure for a sample of air at constant temperature by plotting graphs

1
between P and V, and between P and .
V
Apparatus and Materials Required

Boyleʼs law apparatus, set-square, plumb line, a thermometer, and Fortinʼs barometer

Description of Apparatus

Boyle's Law Apparatus A 100 S
The apparatus consists of a glass tube AB of uniform area of cross- 90 C Reservoir
section closed at one end and connected at the other to a tube CD 80
open at both ends. Pure mercury is poured into tube CD so that a Closed h 70
certain mass of dry air is enclosed in AB. Both the tubes are mounted tube 60

vertically on a wooden board and fi xed vertically on an iron stand
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with levelling screws. The tube AB is clamped in a fi x position
somewhere in the middle of the stand. The tube CD can be made to B 40 D
slide up and down and clamped at any desired position. 30
A vertical scale S serves to measure the height of the mercury surface 20 R Rubber tube
in tube AB and CD. To measure the height of mercury level in tube 10
AB and CD, set-square is used. 0
Scale

Principle/Theory
Boyle's law states that the temperature remaining constant, the
pressure exerted by a given mass of a gas is inversely proportional
to its volume, i.e. Fig. 3.1: Boyle's law apparatus
1
P ∝ V or PV = constant
So, the graph between P and V will be a rectangular hyperbola and the graph between P and 1/V will be a
straight line.

Procedure
1. Set the apparatus with wooden board vertically with the help of levelling screws.

2. The pressure of enclosed air in tube AB is measured by noting the diff erence (h) in mercury levels in
two tubes.

This is done by using a set-square as shown in Fig 3.2.
h = Y – X

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