4/28 week 10 day 1 Capacitors and Capacitance

Quiz:

at the beginning of the class, we did a quiz about the Kirchhoff's law.
We use Kirhhoff's Current Law and Kirchhoff Voltage Laws to find 3 equations to find the voltage, current and power of each line, and find the total power of them.

in this photo ,we begin to learn Capacitance. it can store charges, the unit is F, the symbol is C.
in this photo, Q is charges and V is voltage, and we know the equation Q=VC, and we can find the work done by capacitanor is W= 1/2*V^2*C.

in this photo, we measure the capacitance of different thickness of book, and we make a graph and find that C=k/d (d is thickness and K is constant.)

in this photo, we find the 3 things to influence the number of capacitance, they are area, thickness, and permittivity  the equation of C=kEA/d.

in this photo, we use the equation we find and calculate the area of the capacitor.

in this photo, the professor gives us two capacitors and we make them series and parallel, and measure their capacitance and we find the two equations in the photo.

Then we use the equations we find to find the total capacitance in this graph is 6.5 uF

in this photo, we redraw the graph and find the totoal capacitance is 52nF

Then we use the equation Q=CV to find the charge in every capacitrance
then we calculate the Voltage of C3 and find its charge is 7.32*10^-7C

Then in this photo, we find the total work by battery if all capacitors are charged, the equation is 1/2*C*V^2
Conlcusion:

Today in class, first, we did a quiz and reviewed the basics of how to calculate current and power in a circuit using Kirchhoff's Laws. We also learned about capacitance and how it functions in a circuit, by seeing how changing different variables affects capacitance, and how to compute total capacitance of circuits. When there are capacitances in series, the total C=1/C1+1/C2+…..; When there are capacitances in parallel, the total C=C1+C2+…… At the end of the class, we did an experiment about a culmination of capacitance, as well as recalling various rules about potential difference through a circuit.