The Lights are On!

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Circuits:  A Bright Idea!

Today in class, we talked about electrical circuits and examined the effect of including two lamps in one circuit.
We found that when a circuit includes two lamps in series (one right after the other), the first lamp shines more brightly the second. Because we know that electric circuits are a way to convert electrical energy into another form of energy – in this case, light energy – we learned that the second lamp is dimmer because the first lamp converts some of the electric potential energy into light energy. The second lamp therefore has less potential energy to convert into light.

When the lamps are wired in parallel instead (each on its own branch of the circuit), they shine with equal brightness, because in this scenario, both lamps convert the same amount of electric potential energy into light. But we noticed that the lamps in parallel do not shine as brightly as a single lamp in a simple circuit. Ask your student why this is!

Many students also successfully wired a three-way switch into a parallel circuit, so that they could alternate which of two lights was switched on, and a few even wired two three-way switches together to create a “hotel switch”.  Nice work, everyone!


Dr. Catherine Sukow

Dr. Sukow's interest in science education began when she was a teenager, with an extended visit to San Francisco's Exploratorium. In college, she had summer jobs in a similar, smaller, museum. She focused her Master's research at NCSU on the structure of metal silicides on silicon, and her Ph. D. work at Brandeis on the structure of crossbridged actin bundles. While volunteering in her childrens' schools, she was reminded how much fun it is to teach science, and is happy to be teaching now with Science from Scientists. In her spare time, she also enjoys yoga, choral and solo singing, and attempting a variety of international cuisines.

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