3.3 Introduction to electronics

• Energy band theory
• Conductors, insulators and semiconductors
• Intrinsic and extrinsic semiconductors
• Formation of n-type and p-type semiconductors by doping
• Superconductors
• Applications in day-to-day life

• explain the meaning of insulator, conductor, semiconductor and superconductor
• distinguish between insulators, conductors, semiconductors and superconductors
• investigate the electrical behaviour of conductors, semiconductors and insulators with varying temperatures
• explain intrinsic and extrinsic semiconductors as used in physics
• explain the formation of n-type and p-type semiconductors from intrinsic semiconductors
• describe the applications of conductors, semiconductors, insulators and superconductors in day-to-day life
• appreciate the applications of conductors, semiconductors, insulators and superconductors in day-to-day life

“What makes silicon so useful that an entire industry is named after it?”

“Why does a semiconductor conduct better when it is heated, unlike a metal?”

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1. Why some materials conduct and others do not
   40 min · 2 practice tasks · quiz
   One diagram explains conductors, insulators, semiconductors and the strangeness of superconductors.
2. Semiconductors, doping and where they are used
   40 min · 2 practice tasks · quiz
   How adding a trace of an impurity turns silicon into the most useful material in modern technology.
3. Resistance and temperature
   40 min · 1 practice tasks · quiz
   A fair test: how a metal wire and a thermistor change resistance when heated, and what the graphs show.
4. Superconductors and cooling
   40 min · 1 practice tasks · quiz
   Zero resistance below a critical temperature, why MRI uses it, and why power lines still do not.
5. Electronics around us
   40 min · 1 practice tasks · quiz
   Choosing conductors, insulators, semiconductors and superconductors for real Kenyan jobs.
6. Why silicon runs the world
   40 min · 1 practice tasks · quiz
   The inquiry answered: silicon can be switched, doped, purified and oxidised - and it starts as sand.