4/14/15 - Electric Potential

This class session starts off similar to last weeks where we are given batteries, wires, and light bulbs. We found that putting them in different configurations yielded different results in the brightness of the bulbs. If the bulbs are in series, then the bulbs are dimmer than if they were in parallel configuration.

We take our well known induction heater that we know to have an output of about 300 Watts out of a wall socket and hook it up to a voltage supply. We then heat a small bowl of water and record its temperature change in LoggerPro.

We set a linear fit to the graph and, using the slope, we found the power of the induction heater.

Second run with the voltage doubled, we can clearly see that the power is not just doubled from the voltage being doubled.

Since we have Power = Voltage x Current and we also have Voltage = Current x Resistance, we found that though the voltage double, the resistance stays about the same; then we know that the current is also doubled and therefore, the power should be almost quadruped. The graph doesn't quite should a factor of four, but it explain how it would increase given only a change of the voltage.

Professor Mason testing the resistance of skin on students, we found Robert to not be very resistant.

Now given our resistance rating, we found how much current would actually go through us if we were shocked by a standard 120V wall socket using the formula V = IR.

Now if there was an electric field and we wanted to find the work to get from one point to another, we can see that the work done is path independent, and the same amount of work will be done regardless of the path taken.

Now we rated the work done by each path the particle takes. Depending on the cosine of the angle the path makes with the electric field, it determines the amount of work done by the movement.

Given our general formula for work, Force x Distance, we can substitute in out electric field and find an integral that we can modify to find voltage.

Here we have the general form for electric potential from an infinite distance to a distance r. The diagram depicts a charge with a lines perpendicular to the electric field.

Now using this formula and superposition, we can find the net electric potential at any given point such as the example above. There we have two point charges and two observation locations, we find the potential at each point.

We were also assigned a VPython project that's due in a week, Professor Mason kindly corrected our definition of plagiarism for us.

Here's what Mario actually wrote.