Who invented the light emitting diode what purpose does it serve

Which is special about a dc circuit ? a. it has both series and parallel components b. it has only series or only parallel components c. charge moves in a single direction d. charge moves back and forth quickly

Aproduction line at v. j. sugumaran's machine shop has three stations. the first station can process a unit in 7 minutes. the second station has two identical machines, each of which can process a unit in 16 minutes (each unit only needs to be processed on one of the two machines). the third station can process a unit in 10 minutes. ▼ is the bottleneck station, with a bottleneck time of nothing minutes per unit (enter your response as a whole number).

What is the relationship between wavelength of light and the quantity of energy per photon?