Answer: Light to electricity (photons creating electron-hole pairs separated by p-n junction field).
- A Heat energy directly into electrical energy, in the manner of a thermocouple junction
- B Light to electricity (photons creating electron-hole pairs separated by p-n junction field)
- C Electrical energy back into emitted light, in the manner of a forward-biased LED
- D Stored chemical energy directly into electrical energy, in the manner of a battery
Correct answer: B. Light to electricity (photons creating electron-hole pairs separated by p-n junction field)
Explanation: Photovoltaic: photons absorbed create electron-hole pairs. Junction built-in field separates carriers. Electrons go to n-side, holes to p-side creating current.
Conductors have overlapping bands, semiconductors have a small energy gap that can be bridged by heat or doping, and insulators have a large gap that blocks conduction.
Concept context
Band theory, p-n junction, diodes, transistors, logic gates, and integrated circuits.