It's number three on your worksheet. ;)
A camera flash or lighting bolt because stored separated positive and negative charges --> caused them to do work by briefly lighting a bulb as the separated charges moved back together
The U.S. Environmental Protection Agency (EPA) standard for nitrate in drinking water is 10 milligrams of nitrate (measured as nitrogen) per liter of drinking water (mg/L). * Drinking water with levels of nitrate at or below 10 mg/L is considered safe for everyone.
Both the technician are correct.
All the driving force in the universe always flow from the higher body to lower body, until unless acted by external forces. Which means heat always flow from a hotter body to colder body, high pressure always flow to low pressure.
Therefore the both the technician are correct.
Break the circuit and apace a meter actually within the circuit.