College-Prep Physics: It was sunny out today! So we poked a hole in the side of a copy paper box to make a pinhole camera. Aimed our cameras at the sun and measured the resulting image in order to determine the true size of the sun. The copy paper box worked beautifully: the sides with the hole and the screen are always parallel; it’s easy to aim the camera directly at the sun — lay box on ground and lift up/turn until box shadow is square; for the size of the box, the image of the sun is exactly 1/2 cm across (so it fits perfectly within 1/2 cm graph paper). We didn’t do anything fancy with foil like I’ve seen for other pinhole cameras on the internet. Should we have? Why?
Conceptual Physics: Students finished the diode circuit simulation activity from yesterday. One group came up with a possible bike generator circuit that will charge the battery and light the bulb while pedaling, and will also use the battery to light the bulb when the pedaling stops.
College-Prep Physics: We were supposed to go out and explore pinhole cameras, but it was cloudy. So today we explored gravitational force with a sim from The Physics Classroom: http://bit.ly/gravitysim. Students are doing a similar analysis like they did with light intensity a few days ago. Handout here: ACTIVITY Universal Gravitation 2013
Conceptual Physics: I found a great circuit simulation which has diodes (PhET doesn’t have diodes): http://bit.ly/acdclab. Students explored diodes and AC circuits with this today. Hopefully it will allow them to understand diodes better and be able to come up with a draft of their modified bike light generator circuit. Handout here: DiodeCircuitSimLab2013
Conceptual Physics: Here a bike light generator is connected to a voltage probe in Logger Pro. The red graph shows what we saw yesterday — the voltage cycles positive and negative (AC). The blue graph shows what happens when a diode is added to the circuit. Diodes will be important later when we use the bike generator as a battery charger.
College-Prep Physics: Based on students’ work to the M&M (light collection) lab and the properties of light activity from prior days, I decided to do a review of mathematical relationships. The handout is here: MATH RELATIONSHIPS