Day 17 DC circuits

At the beginning of the class, we need to predict what happens if the switch is turned on in this circuit problem.

Our predictions were that #1 and #2 bulbs will stay the same and #3 bulb will stay off.

This picture shows that our prediction was right, #1 and #2 bulbs stayed the same as the switch is turned off because the voltage is the same. And #3 bulb is not on because the voltage is 0.

This is another practice exercise on circuit, we predicted that two bulbs will be the same as the switch is on.

As a result, our prediction was right because on the top bulb there is a parallel battery so the voltage of the two side does not change. And for the bottom bulb, the parallel battery has no effect on it. So it stayed the same.

In these two picture we were performing an activity where we tried to arrange the circuit to control the bulb to be bright or dim. And we found that we should make the bulbs parallel to make the bulbs brighter.

In this picture, we practiced four problems on circuit.

First: 

We made the circuit as drawn on the top left corner, and we found the voltage of source = Vr1 + Vr2.

Second:

For the second circuit we measured the voltage of source and the current of source Ir1 and the current of Ir2 and Ir3, and we found that Ir1 = Ir2 = Ir3.

Third:

We made the circuit as drawn as the top right corner. The two resistors are place parallel, and we measured that the voltage is Vr1 = Vr2.

Fouth:

We measure the current of the source I1 and the two resistance Ir1, Ir2, and found that I1 = Ir1 + Ir2.

In this picture, it shows 4 different kinds of colors in one resistor. The first three are certain which we can measure their resistance R, and the last one is the uncertainty of R.

We predicted the 4 different resistance and their uncertainties. The resistance is not good.

In this picture, all the resistances are the same as 620 ohm, and we calculated that the different R of 4 graphs.

In this picture, we calculated the total R of the circuit by using the laws of parallel and series.

This picture shows the last exercise we did, we used the Kirchhoff's Law to solve this problem.

Conclusion

In today's class, we have looked at two different arrangement parallel and series on a DC circuit and the relationships between voltage, current, and resistance. We also learned Kirchhoff Rule and the Loop Rule to apply on the problem so we are able to solve the circuit problems by calculating the amount of current flowing through a circuit, and total resistance whether the circuit is in parallel or series arrangement.