One of the most helpful visual aids that I employ throughout this unit on electromagnetism is the hula hoop.
I use the hula hoop to demonstrate the application of the right-hand rule for a current-carrying loop generating a magnetic field. I later use the hula hoop to demonstrate flux and how the orientation of the loop changes the flux. I keep it handy throughout the unit!
Today, we started investigating electromagnetic induction in AP Physics 2. I demonstrated how inserting a magnetic into a solenoid resulted in a current in the solenoid that could be measured with a galvanometer. We then discussed as a class what variables may affect this induced current. The students thought of enough variables such that each of the six groups qualitatively investigated a different variable. After investigation, each group demonstrated their investigation and shared their results with the rest of the class.
Today was a half-day with 27-minute classes. Good day for a quiz to check if AP Physics 2 students are where they should be at about the midpoint of the electromagnetism unit. I didn’t take a good photo of students during the quiz; so I took a photo of the classroom floor after moving all of the desks and chairs out of the way. The concrete floor is marked with tape outlining half of the FIRST Robotics Competition Recycle Rush field. It helps to visualize and try various strategies when you can stand on a half of a full-sized field!
Today in AP Physics 2, students determined the mass of the electron. The students deflected an electron beam in a vacuum tube with the magnetic field of the solenoid. By measuring the current in the solenoid, the accelerating potential in the vacuum tube, and the radius of curvature of the electron beam, students were able to calculate the mass of the electron. There is a lot of uncertainty in the radius measurement, but the calculated mass is still fairly close to the expected value!
I always get a kick out of watching an entire class applying the right-hand rules during peer instruction, like today, a quiz, or an exam. I joke that they should stretch first so they don’t injure themselves with all the twisting and turning!
Today I was off-campus for a meeting for our district’s Digital Learning Initiative (1:1 pilot). The AP Physics 2 students whiteboarded on their own. One of the problems I assigned was a bit more challenging that I realized requiring the application of the Law of Sines and an equation that we hadn’t seen previously. Probably not the best choice for what I wanted them to focus on.
##magnetism ##setbacks ##whiteboarding
For one of today’s formative assessment sketches, I asked students to sketch the magnetic field of a current-carrying wire given the direction of current in the wire and draw the force vector on a positively charged particle near the current-carrying wire. I’m definitely gaining more insight into which students are still developing their understanding by seeing their sketches. I’m also better able to address minor issues and questions that I think I would normally miss. For example, some students wanted to draw lines between the x and dots representing the magnetic field of the current-carrying wire rather than just drawing the x and dots.