Thermodynamics > Heat and the First Law > Heat Capacity DCS# 4B10.70

RUCHARDT'S APPARATUS



APPARATUS
10.4 L flask with glass tube 214-02-E
stopwatch 101-05-D4
steel ball 214-02-E
chamois 214-02-E
alcohol 202-02-A
magnet 214-02-E
level
101-05-D4

DESCRIPTION
The ball just barely fits inside the precision bored glass tube and, when dropped into the tube, will oscillate on a cushion of trapped air.  The period of oscillation of the ball can be used to determine the ratio of specific heats, cp/cv, of the air inside.

NOTES
cp/cv = 4 π2mV/(A2PT2 )
where m = mass of ball
volume of air, V = 10.4 l
cross sectional area of tube, A = 2.0x10-4 m2
P = atmospheric pressure

Use the chamois and alcohol to clean the inside of glass tube and the steel ball before use.  

Use a level to make sure that the tube is vertical.

There is a rubber mat inside flask to protect it when the ball drops.  Use the magnet to retrieve the ball or remove the stopper from the bottom of the flask.

REFERENCES

Klinger Instruction Sheet