A good example of theory can be found at
http://www.site.uottawa.ca/mathasatool/01unit/12topic/focus/voltage_current/p09.htm. These are equations that are never used in industry.
Industry needs people who understand capacitors: 1) The voltage ratings must always be twice the applied voltage (except tantalum requires three times), 2) Ceramic capacitors have higher accuracy, higher voltage tolerance, polarization independence, more tolerant to temperature changes, longer life, 3) non-ceramic capacitors have larger micro-farad specifications, 4) Ceramic capacitors have low ESR (can handle high frequencies), non-ceramic cannot.
Some good examples that are not common knowledge:
1) Ground Planes and Voltage Planes --- necessary for almost all products (especially for miniature products) - and for EMC.
2) Common Mode Chokes --- necessary for EMC in some cases.
3) Tin Whiskers --- Failure does not show up until the product has been shipped to customers - two satellites in outer space failed because of tin whiskers =>
https://nepp.nasa.gov/whisker/failures/.
4) PCB Dendrite Growth --- Product works initially, then can fail after the customer uses the product for a few months or longer - I hope it does not happen in an airplane.
5) Tantalum Capacitor voltage needs to be overrated by a factor of three --- Resulted in a fire, one time, for an IBM computer control panel - could have resulted in a lawsuit.
6) Counterfeit Components --- Product works initially, then can fail after the customer uses the product - or fails over temperature changes.
These are important in the electronics world.