A simple question, can you make this light bulb turn on with a battery, a wire, and nothing else? Well, we sort of got it. The class starts off by allowing the students attempt this task. After successfully lighting it up, we concluded a few things on the whiteboard.
More pictures of lighting the bulb up.
Two circuits that will make the bulb light up and two that don't. The two that work have the the bottom of the bulb touching the battery and the wire connecting the side of the bulb.
Two two that don't work doesn't finish the connection back to the battery and the second doesn't allow the charge to pass through the filament.
This is an electroscope. It has a conducting rod on top that can accept charge and will allow it to pass downward to two metal plates. Professor Mason touches the rod with a charged rod and gives the rod a charge. The charge flows down and, since there are two plates, allows each plate to repel one another as shown in the picture above.
Given these observations, we predict what would happen if the top of the battery was applied to the rod. Our prediction was incorrect, when the battery was applied on both sides, nothing had happened.
We also explain why the bulb has to be connected the way it was in order to work properly. The charge has to have a steady rate of flow in order the work to be done.
In this picture, we are given the analogy of water to better understand current. We find two aspects that would increase this water flow in a given amount of time. The two we came up with for a waterfall were the height of the waterfall and the amount of water flowing through.
This is analogous to the Voltage and Current of the power flow.
Further down, we are given that the power is Voltage x Current which has units of Joules / Coulomb and Coulombs / Second - canceling out to Joules / Second.
Here, we hook up our original setup to a amp-meter. Ours was a little faulty, but we found the average amperage going through our circuit according to the meter.
The measured values are with the meter hooked up before the bulb and afterwards. We find that there is almost no change in the current so there is no current lost after flowing though the bulb.
Here we define the four things that we should know in order to find the charge, and their common symbols used.
Given the formula for current, we're asked to find the drift velocity of the electrons passing through the wire. By rearranging the formula to use the givens, we find that the drift velocity is relatively small compared to speeds we normally see in mechanical physics.
Here is a induction coil from a toaster, it's hooked up to a voltage supply and a watt-meter.
The graph shows the relation as voltage was changed during the experiment, Through the graphs we can see that voltage and current have a generally linear relationship.
Our predicted graph before the experiment, we thought it would have a linear slope with an inital vlaue.
Since our itinal prediction was correct, we found the slope to be voltage over current and a differential version as well.
We then set resistance equal to this slope and found the units of Ohms, being voltage over current.
Here we try different coils of resistance made of different materials and length. We connect them to a multi-meter set for ohms.
After a various amount of tests with diffident lengths and materials, we find a general formula for resistance. We found that the resistance is proportional to the length and inversely related to the area. Given these, we set the resistance equal to the \rho density of the material, length of the segment and all over the area of a cross-section.
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