activity 2 quantum tunnelling composites 3 sessions...
TRANSCRIPT
Activity 2 Quantum Tunnelling Composites 3 sessions
Club Leader Notes
Activity 2 Quantum Tunnelling Composites
Resources (for 5 groups)
Activity 2 Quantum Tunnelling Composites
Experiment 1: Using QTC as a simple switch to control a motor or bulb
Activity 2 Quantum Tunnelling Composites
Experiment 2: Using QTC to control the speed of a motor and the brightness of a bulb
Activity 2 Quantum Tunnelling Composites
Experiment 3: More sensitive control of QTC
Activity 2 Quantum Tunnelling Composites
Experiment 4: Using QTC to vary the colour of a tri-colour LED
Activity 2 Quantum Tunnelling Composites
SMART Challenge!
SMART Spark!
Questionnaire
Fact Sheet Quantum Tunnelling Composites
Quantum tunnelling composite, or QTC, is an amazing substance. When in its resting state QTC is
an almost perfect insulator; when pressure is applied, QTC becomes an extremely good, metal-like
conductor of electricity. This strange behaviour is all down to its structure. QTC is a composite
material, containing very small particles of metal embedded in non-conducting binding material
(such as silicone rubber). In its resting state, the metal particles are too far away from each
other to allow electrons to pass between them, so electricity cannot ‘flow’ through it. When
pressure is applied, the metal particles are squeezed closer together, and electricity can now flow
through the QTC. The particles don’t actually touch when they are squeezed – they are still
separated by a minute layer of binding material. But a strange phenomenon called quantum
tunnelling takes place, where electrons ‘tunnel’ through the binding material from one metal
particle to another. This is made easier because the metal particles are spikey.
QTC was discovered by accident!
In 1997, David Lussey, a research engineer in Darlington, was trying to make an adhesive that
would conduct electricity. The substance he made wasn’t a conducting adhesive, but a substance
with unusual electrical properties, now known as QTC. A company called Peratech was set up to
develop the material and its commercial applications. Read about it on
http://www.practicalphysics.org/go/Resources_18.html
Applications
QTC is a versatile switching and sensing medium. Due to its unique electrical properties and
flexible manufacturing possibilities, it has very many potential applications. Here are just a few: