Download Physics experiments

Teachers' TV tips sheet
Title
Physics experiments instructions and tips
Author
David Richardson, the Institute of Physics
Associated Teachers’ TV programme
KS3/4 Science: Demonstrating Physics
Programme description
Show-stopping physics experiments to keep students interested
Note to teachers
This tips sheet was not created by Teachers' TV but the author has allowed us to publish it
here to be used for educational purposes
Physics experiments instructions and tips
Forces, motion, pressure and density
The heavy box with helium balloon
Curriculum link: Turning moments and centre of mass
Brief instructions: Pretend to struggle to carry in a heavy box that is
empty except for a large mass in the corner of the box. Placing the corner
of the box on a table allows to it to hang unnaturally off the edge.
Attaching a helium balloon can further reinforce this
Ideas reinforced: This allows pupils to question an odd situation and
apply their common sense. The scientific principles behind what they see
can then be brought out
Target audience: This makes an excellent starter to a lesson on
moments or a good plenary at the end to get pupils to reinforce and
verbalise what they have learnt
Tips:
 Ensure the weight is heavy enough
 Tape the weight inside the corner of the box
 Make it look like the whole box is heavy
Disappearing metal ball in rice
Curriculum link: Floating and sinking, density
Brief instructions: A heavy ball bearing will sink into rice when shaken.
A polystyrene ball will float to the surface of the rice when shaken. The
two ideas can be combined to make a nice illusion that demonstrates
excellent principles of floating and sinking at KS3
Ideas reinforced: Shaking the glass of rice shows nicely the motion of
particles in a liquid. The ball bearing sinks because it is denser than the
rice around it. The polystyrene floats because it is less dense than the rice
Blowing bubbles with helium
Curriculum link: Floating and sinking, density
Brief instructions: Attach a rubber tube to a helium balloon and use it to
blow bubbles. These rise rapidly to the ceiling
Ideas reinforced: Less dense gasses rise
Flying tea bag
Curriculum link: Convection
Brief instructions: Remove the tea leaves from a Twining’s fruit tea
infusion, leaving a cylinder of paper. Stand the cylinder on its end and
light the top. It will rise to the ceiling
Ideas reinforced: This demonstrates nicely the idea of convection. Use
as a starter to get pupils ideas or as a plenary where they can explain
what they see from what they have learnt
Lifting a wine glass with a balloon
Curriculum link: Air pressure
Brief instructions: Inflate a balloon in the top of a glass and you can lift
it off the table. Lubricate the balloon and you can turn it while still lifting
the glass
Ideas reinforced: Pupils find it hard to see that air pressure exists. This
demonstration can be used to get pupils thinking about what is holding
the balloon in the glass
Expanding marshmallows
Curriculum link: Air pressure
Brief instructions: Remove the air from a wine bottle full of
marshmallows using a wine preserver and the marshmallows expand to
about twice their original size
Ideas reinforced: Pupils are always impressed with this experiment, and
it gives them an excellent opportunity to apply their ideas and
understanding of air pressure
Tips:
 A wine preserver and bottle make it easier to demonstrate
 Long thin marshmallows don’t stick in the neck of the bottle
 The effect is more noticeable when letting the air back in
Cartesian Diver and ketchup
Curriculum link: Pressure, density, floating and sinking
Brief instructions: An inverted combustion tube in a sealed lemonade
bottle will sink and rise as the sides are squeezed. Tomato ketchup
sachets in a lemonade bottle will also act as Cartesian divers
Ideas reinforced: Pupils can bring together their ideas from different
topics. A good revision activity
Tips:
 Ensure the combustion tube has the exact amount of water to make
it float
 Make sure the sachet floats
 A standard 2-litre bottle works best
Van de Graaff generator
Tips:
 Have a wooden metre ruler on hand to discharge the pupils
 When charging a person on a plastic box, keep free hand away from
earthed metallic objects


Keep pacemakers, hearing aids and electronic equipment away
from the generator
Consult CLEAPSS for further information
The electromagnetic spectrum: microwave with light bulb
Curriculum link: Metals/water/fat
Brief instructions: Stand a household light bulb in a beaker of water.
When the microwave is turned on the light will come on
Safety: Do not reuse the bulb once it has been used in the microwave.
Putting boiling tubes of water and sunflower oil into the microwave will
demonstrate that microwaves heat water but not oil
Tips:
 Ensure there is water in the beaker
 Only switch on for about five seconds
 Download the CLEAPSS risk assessment of this experiment from the
resources and support materials page
 Consult CLEAPSS for further information
The electromagnetic spectrum: measurement of speed of light
with tortillas or egg
Brief instructions: If you invert the turntable plate in a microwave, it
will stop spinning. Spread cheese onto a tortilla, or egg white on a plate
and put into the microwave. Areas of the cheese will melt, or areas of the
egg white will cook, while others won’t. Use the distance between these to
calculate the speed of light. The frequency is printed on the back of the
microwave oven