# Day 147: Watts in the Box?

Conceptual Physics: Students attempted to figure out the wiring inside 8 different mystery circuit boxes by unscrewing the 4 light bulbs for each box. (Well, really 7 because one box needs repair.) I built them a number of years ago with a lot of help from my dad. If you’re not very handy, you can rewire bar light fixtures purchased from a hardware or lighting store. (See: Mystery Circuit Box and Make a Mystery Circuit with a Bar Light Fixture.) I used 15-watt bulbs that have a standard base (clear glass whenever possible). They are a bit more expensive, but they never get too hot to touch. Students enjoyed solving these circuit puzzles!

College-Prep Physics: After graphing the data from yesterday’s activity, we saw that when objects have the same apparent size, they also have the same size/distance ratio. We used this concept to create a “handy tool” for determine the size or distance to unknown objects. Students were challenged to determine the distance to the doors at the end of the hallway and to determine the height of the flagpole. In the picture above, the width of my pinky finger held at arms length is the same apparent size as the height of the doorway at the end of the hall. How far away is the doorway? What assumptions are you making? Handout: A Handy Measuring Tool 2013

AP Physics C: No class. All students were taking the AP Calculus exam today.