replace its predecessor, the 30-pin dock connector, the Lightning connector is used to connect Apple mobile devices like iPhones, iPads, and iPods to host computers, external monitors, cameras, USB battery chargers, and other peripherals.
Answer: You're converting electrical energy from the wall outlet into chemical energy inside the battery, plus a bit of wasted heat energy, since battery charging is less than 100% efficient.
Most likely the second one (sand letting water run through it) because if you are trying to determine how what moves through soil You would want the one the one that can do that:)
