Exploration of Circuit Phenomena

Students were given a pile of batteries, wires, and bulbs to create any kind of circuit they want.



First, they decided to connect five batteries to four bulbs (1 series, 3 in parallel). The students predicted that the single bulb would be dimmer because there is more resistance, because the bulb is not connected directly to the battery.



We found that only bulb #1 would light when the entire circuit was connected. However when we made a direct connection between the battery and the three bulbs in parallel, all three bulbs were able to light.



One of the students said, “Bulb #1 will be brighter because there is less resistance with the three bulbs, when they are connected with separate paths. There is less resistance and more paths for the current to move through. With the five batteries, there isn't enough power to light all four bulbs. When 3 bulbs connected directly to battery, they light.”

Powerful Idea: More current is flowing through when we have one bulb in a circuit than two bulbs. The bigger the obstacle, the smaller the current.

After the students had a firm understanding of what they'd just learned, Emily asked, “How can we represent what's going on here mathematically?” She discussed the history of the word “volts” and where the concept comes from, and introduced the symbol for voltage: V.

Voltage is having something that can drive current through the circuit.

Each “thing” that is moving through the circuit is carrying with it a certain amount of energy. The amount of energy that is being carried = voltage.

Ohm's Law:

I = Current
V = Voltage
R = Resistance

I = V/R