STE 15076 Experiment Pack - Atmospheric Pressure and Vacuum

INTRODUCTION

This useful and straightforward Experiment Pack provides all necessary apparatus, with Instructions and Teaching Guide for 8 experiments covering the topics of atmospheric pressure as weight of air, forces generated by pressure differences and vacuum, and the behaviour of sound waves as pressure is reduced.

TOPICS COVERED

1.      The vacuum pump

2.      Atmospheric pressure

3.      The diaphragm bursting experiment

4.      The Magdeburg hemispheres

5.      The balloon experiment

6.      The flask experiment

7.      Propagation of sound waves

8.      Newton’s tube

EQUIPMENT PROVIDED

1 U tube with rubber stopper

1 Newton’s tube

1 diaphragm burster

1 alarm

1 silicone grease

1 Magdeburg hemispheres set

1 balloon

1 manual vacuum pump

1 pressure plate

1 bell jar

1 vacuum hose

1 test tube

1 50cc flask

1 50cc beaker

1 instruction manual and teaching guide

EXAMPLE EXPERIMENT

(all worksheets have necessary diagrams)

MAGDEBURG HEMISPHERES

Another experiment useful for proving the presence of air pressure is that of the Magdeburg hemispheres. This apparatus consists of two metallic hemispheres that can fit closely together. At normal air pressure it is easy to separate them, since the internal pressure balances the external. If the air inside is extracted, the balance is no longer existing and separating the hemispheres requires the pull of two strong people (or even, if the hemispheres were to be large enough, horses).

EXPERIMENT 4

Required apparatus

1 vacuum pump, 1 pressure plate, 2 Magdeburg hemispheres, silicone grease

Step 1

Rub silicone grease on the rim of both hemispheres, to ensure perfect air-tightness. Rub grease also on the rim of the support, to ensure air-tightness with the plate (figure 7).

Step 2

Place the hemisphere’s support on the plate and turn it applying pressure on it, so that a perfect adhesion is ensured. Close the plate’s back tap and open the tap connected to the pump.

Press on the pump’s piston about 10 times (figure 8).

Step 3

Close the hemisphere’s tap and open the pump’s back tap, to let air enter into the hemisphere’s support. The support will be easily detachable from the plate. On the other hand, a very strong pull will be required to separate the two hemispheres (figure 9).

You can work out the force required to separate the hemispheres:

Force = pressure difference x area.