I just had a look at the data of our latest experiment assignment for our students. Just like in our previous collective measurement of pendulum frequencies, the students were supposed to submit their results through an online form, so we can combine all the data to test a model that will be discussed in an upcoming lecture. This time, they should measure the magnetic field generated by a current loop.
Since we could not expect that every student has got an adjustable current available, we instructed them to simply use an AA battery (non rechargeable, non Lithium, etc. for safety reasons) and connect it to any cable (like the USB cable in the picture above). After finding the location of the magnetometer in their phones, they simply should create a loop with the magnetometer in its center and measure the change in the magnetic field perpendicular to this loop. Repeat five times with varying radius and submit the results:
Since we do not know the actual current used in this experiment (at 1.5V this still depends on the cable and the battery’s internal resistance), we told them to include one measurement at a radius of 5cm and plotted the ratio B(r)/B(5cm) of the B field at any radius to the one at 5cm, to eliminate this unknown. Also, the plot only shows the absolute value as some students submitted negative changes.
I am quite satisfied with the results and am looking forward to the lecture in which we can presented the collective data to the students.
Woohoo, we have reached 100.000 installs (combined, Android and iOS) in less than a year. This is so amazing, thanks to you all! Please help us spread the word about phyphox even further by sharing your favorite experiment, a tweet/post/youtube video or just a link to our site with friends and colleagues – on the web or face-to-face.
He has created a phyphox experiment file which allows you to measure a hysteresis curve of a coil with an iron core using your phone’s magnetometer. In order to measure it as a function of the current through the coil he uses a simple method that could certainly be applied to other experiments as well – He simply uses a second coil without an iron core, which produces a magnetic field on another axis of the magnetometer, which is proportional to the current.
This is the first extensive contribution to our Wiki and this is exactly how the Wiki is meant to be used. If you have an experiment you would like to share, simply create a user account and start adding your article/experiment/note to the Wiki. Even if it is just a small contribution, we will welcome it glady.
There will be a short contributed phyphox talk and a poster at the AAPT Summer Meeting in Cincinnati from July 22nd till July 26th. If you want to meet me and discuss smartphone physics, I will be happy to meet you at a convenient time at the meeting (the poster session might be a little short and busy) – just send me an email (firstname.lastname@example.org).
We have just published an article in the German journal “Physik in unserer Zeit”, presenting phyphox and discussing its abilities to create customized experiments and remote control. We demonstrate this using a wheel rolling down a hill with the smartphone placed in its rim. In this experiment, phyphox autonomously determines the radius of the wheel and its velocity (similar to the roll experiment shipped with phyphox).
If you want to try the experiment described in the article, you can open it directly in phyphox or download it. The experiment expects the phone to be as close to the outer radius of the wheel as possible and rotate about the x axis.
Many thanks to the organizers of the MNU convention and everybody who attended our talk, our booth and our workshop! Getting all experiments ready for each event was a little stressful, but all the positive feedback was absolutely worth it. We really enjoyed it, thanks a lot!