Question

Suppose you have a circuit with a 10 volt battery hooked up to a 100 ohm light bulb and a variable resistor of R ohms. The light bulb and the resistor can be hooked up in series or parallel. Draw both these circuits and label them as series or parallel and with the values of each component.

1. Now, solve for the current in the light bulb in each of these circuits for R = 10, 100, and 1000 Ohms.
2. Given the current in the light bulbs above. Solve for the power in the light bulbs in the six cases. (You may wish to use a different equation for power, remember there are 3).
3. How does the brightness of a lightbulb depend upon the resistance in the variable resistor in each case?
4. Which one of these circuits would be useful as a dimmer switch? What might be a drawback to using this method to dim lights? (It might help to think about where all the power goes when you dim the light)

Answer 1