Power Lab Writeup

Lemon

A lemon battery works by exploiting the fact that some metals give up electrons more easily than others. In the lemon battery, a chemical reaction among the acidic lemon juice, copper, and zinc creates a current. Since copper gives up its electrons rather easily and zinc receives those electrons, there is a voltage difference between the copper coin and zinc nail. This voltage difference allows a current to run through the lemon battery.

Solar Panel

The solar panel works as a voltage source because it makes great use of silicon. Silicon has an outer shell with 4 electrons and it always looks to find 4 additional electrons to complete its shell. The silicon used in a solar panel has impurities which means there are other atoms mixed with silicon such as phosphorous. Since phosphorous has 5 outer electrons, there is a leftover electron when it bonds with silicon. When these leftover electrons are hit by the heat (energy) from sunlight, they begin to wander randomly while carrying an electrical current. These electrons "rush" to the holes created by the silicon atoms bonding with boron which only has 3 outer electrons. As a result, voltage is created when the electrons move in the solar panel.

Hand crank generator

The hand crank generator works through magnetic induction. A coil of wire rests inside several magnets. When a person turns the crank, the coil begins turning and the magnetic flux through the coil changes. Because of this changing magnetic field, a voltage will be induced that opposes the change in the magnetic field. This is what lights up the lightbulb. As soon as a person stops turning the crank, there is no change in magnetic flux and therefore no induced voltage so the lightbulb doesn't shine.