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Semiconductors and Superconductivity: Applications in Modern Science
What Are Semiconductors?
Semiconductors are materials with electrical conductivity between conductors and insulators.
Examples: Silicon and gallium arsenide.
Principles of Semiconductors
Band Theory
- Conduction Band: Electrons here conduct electricity.
- Valence Band: Electrons are bound to atoms.
- Band Gap: Energy difference between bands determines conductivity.
Doping
Adding impurities to semiconductors increases their conductivity:
- n-type: Adds extra electrons.
- p-type: Creates holes (electron deficiencies).
What Is Superconductivity?
Superconductivity occurs when a material exhibits zero electrical resistance below a critical temperature (TcT_cTc).
Applications of Semiconductors and Superconductors
Semiconductors
- Electronics: Transistors, diodes, and integrated circuits.
- Solar Panels: Photovoltaic cells convert sunlight to electricity.
Superconductors
- Maglev Trains: Use magnetic levitation for frictionless travel.
- MRI Machines: Generate strong magnetic fields for imaging.
- Energy Storage: Superconducting coils store large amounts of energy.
Example Problem
A solar panel made of silicon generates 5 A5 \, \text{A}5A of current under a potential difference of 10 V10 \, \text{V}10V. Calculate its power output.
- Formula:
P=IVP = IVP=IV
- Substitute Values:
P=5⋅10=50 WP = 5 \cdot 10 = 50 \, \text{W}P=5⋅10=50W
Practice Questions
- Explain the role of doping in semiconductor devices.
- Describe how superconductors are used in MRI machines.
- Calculate the power output of a solar panel generating 2 A2 \, \text{A}2A at 20 V20 \, \text{V}20V.