Frequently Asked Questions (FAQ)

When opening phyphox, it does not explain much, because it is mostly a collection of tools that can be used in a physical experiment. So, in most cases you should already have an experiment on your mind and find that phyphox is just the tool you were missing or, for example as a student, phyphox is the tool that is part of the instructions to an experiment.

Nevertheless, you can explore the experiments in phyphox yourself and if you are interested in physics, you really should. If you open an experiment, you can get a short description from the menu (top-right corner). The description tells you what kind of experiment this is and what you need. It also offers a link to our Wiki with more details on the setup and some trouble shooting. Sometimes, there even is a link to a video, demonstrating the experiment (more videos will be added over time).

If you are unsure, how an experiment works, you should either check out our demonstration videos (not every experiment has got one, but more are added all the time) or the Wiki entry of the experiment. You can also quickly access the right video or Wiki entry directly from the description of the experiment, which you can find when opening the experiment in phyphox and selecting “description” from the menu.

Most of the time, this actually means, that you do not have the sensor. Some typical examples: On some low-cost tablets, there is no sensor besides the accelerometer. On iPhones, there is a physical light sensor, but it cannot be accessed by our app (technically, there is a way to do this, but Apple does not allow apps on their App Store that use this method). The barometer (pressure sensor) is mostly available on newer expensive Android phones and on iPhones from version 6 (but not on the iPhone SE).

The short answer is that Apple does not have an interface to access this sensor.

In fact, iPhones do have a light sensor, but there is no official way for an app to access it. There are some low-level methods, but apps that use these methods are not allowed on Apple’s App Store.

You might find other apps that give you a measure for “brightness”, but those either use the screen brightness as an indirect indicator for a change in the environment’s brightness or they use the front-facing camera instead to give you a direct reading. Since phyphox does not yet support the camera, we cannot do the same.

You should note that there is a subtle, yet important difference between the readings of the camera and the light sensor. The light sensor (on Android at least) measures illuminance in Lux. That is the luminous flux per area onto a surface (in this case the sensor detection area). The camera however, gives you the luminance (especially subtle difference in the English term) which is the luminous intensity per unit area into a specific direction. This is given in EV (exposure value), a unit used in photography and can be converted into more common units if the parameters of the camera are well-known.

Still, the camera only measures luminance and not illuminance. This difference becomes clearer when you consider the following example. Your phone is facing up towards the sun. Camera and light sensor show that it is very bright. Now, if you rotate your phone away from the sun, the illuminance will gradually decrease as the cross-section of your phone (or your sensor’s detection area) becomes smaller until the illuminance reaches zero when your phone is perpendicular to the sun. The camera however will show the same luminance as long as the sun is in its field of view. As soon as the sun is outside the field of view, the luminance drops to zero almost immediately. This strongly depends on the field of view (focal length) of the camera.

There are only very few smartphones that offer a temperature sensor and only some of those offer its data through a common interface. We can only know that there is a temperature sensor if it properly announces itself as “TYPE_AMBIENT_TEMPERATURE”, but many phones declare their own vendor-specific sensor type here, so we cannot guess that it is a temperature sensor.

In fact, we have not yet have a device that properly reports a temperature sensor, which is why we did not include this untested feature. In future versions of phyphox we will implement an experimental support through the “+”-button and custom experiments. Still, the sensor needs to report the correct sensor type.

In the end, temperature sensors in smartphones only make limited sense as they mostly measure the temperature of the device, which heats up on its own. We think that this is also the reason that many manufacturers do not officially support this sensor even though it is actually included in another sensor chip (i.e. the barometer).

The “roll” experiment has been disabled on iOS in June 2018 with version 1.0.13 after it has been a part of phyphox since the very first release more than 1 1/2 years earlier. The update was supposed to only introduce two new translations, but Apple rejected the update because they found that this experiment (which has not changed in all the time) might damage the phone. So, we had to remove it on iOS in order to publish new versions of phyphox.

phyphox runs on every Android device since Android 4.0 and on iPhones since iOS 8.

Please report it to us. Simply write an email to staacks@physik.rwth-aachen.de and describe the problem as good as you can. Do not forget to include details like the model of your phone. If you are willing to help us tracking down the problem by testing a few things, we are especially grateful, but just reporting already helps a lot.

If the problem involves a crash of phyphox, usually Android and iOS offer that you can report the crash through their system. Please do so, as it offers invaluable information that you usually cannot provide on your own (like the exact location in our code where the error occurred). We are still happy if additionally you send us an email, so we can contact you if we need more details or would like to test a solution.

The coordinate system is explained here.

Since the file system on mobile systems is not as freely accessible as on desktop PCs, we strongly recommend that you try different, usually more convenient options. Phyphox can hand your exported measurement over to most of your apps which then can send the file as an email, sync it to a shared folder or transfer it via Bluetooth. Also, you can directly download the data through our remote access function.

If you want to save your file locally anyway, use an app that can take and save your file, like for example Total Commander (Android) (we are not affiliated with this app, so we cannot give any guarantees).

If all you want is save your measurement without transferring it, you should use the “Save state” function. It places the current state of your measurement in the main menu, from where you can open it again and then export or continue your work. – No third-party-app required for this.

Phyphox picks the first supported language from the list of your preferred languages set in Android/iOS. So, if you want a different language, you should set it up in the settings of your phone and if your main language is not supported, make sure that your preferred languages are in the right order.

Here is an example on how this is set up in iOS:

Yes.

To be more precise: The remote interface does not require you to install anything on the controlling device. You just have to enable the remote access in phyphox on your phone. On your second device, you have to open a browser (Firefox, Chrome, Safari, Internet Explorer, etc.) and enter the address shown by phyphox (like http://123.45.6.78:8080) into the address bar of the browser.

If this down not work, it is usually due to network problems – Your devices are not connected to the same network or may not communicate directly in this network. In this case, you can get more information here

Yes, there are. Actually, the access to your experiment is not encrypted or password protected at all. However, it only gives access to the running experiment, so there is no sensible data. You usually only have to worry about this, if you are showing your experiment in front of an audience using the same network as everybody. Then anybody in your audience could mess with your demonstration. In this case, we highly suggest that you should create your own network by setting up a wireless hotspot (see here)

A password protection would protect your experiment from being controlled by somebody else, but it would not protect you from somebody sabotaging your demonstration. The problem is, that your phone and phyphox is not designed to handle many requests simultaneously and if your audience wants to mess with your experiment, they will be able to slow down and overload the remote interface even with a password.

Since the security concern is not about protecting data but about preventing “messing up your demonstration” a password would only give you a false sense of security and complicate the remote interface. Instead, we highly suggest that you create your own network by setting up a wireless hotspot (see here)

You should be able to achieve latencies way below one second. Unless your phone is really slow, higher latencies are usually due to your network. Especially large WIFI networks (like at universities with many users) tend to have a higher latency. You might have a good bandwidth (fast download), but still a higher delay. As an alternative, we highly suggest that you create your own network by setting up a wireless hotspot (see here).

Of course you may. In fact, if you think that your presentation/workshop/training etc. focuses on phyphox enough to be featured by us, please let us know through the email address at the bottom of this page and we will happily add it to our events calendar and our social network channels.

Yes, you can. There are some requirements, though. Please check out our translation page for more information.

If the experiment is already running and you want to document it, please visit out Wiki, where you can deploy your information on your own for everyone to see.

If you need help to create the experiment or if you think that it is worth to be included in the app or featured on our site, please contact as via the mail address at the bottom of this page.

Yes, please. We have opened our source code under the GNU GPL 3 licence and are happy to see contributions by other developers.

We are currently working on a more intuitive and unified solution to this, but for now you have to transfer the file yourself:

After creating your phyphox file, you can either copy it to your device via USB (can be tricky as you need to find your file afterwards with a file browser) or transfer it with any app that allows transfering data. For example, this could be an email or a service like Dropbox, Google Drive or OneDrive. Then you have to find the file in the respective app (your mail app or the one for the service you used) and open the phyphox file from there. Sometimes you need to select “share” to send it to phyphox or, on iOS, “copy to phyphox”

We are currently working on a more intuitive and unified solution to this, but for now you have to transfer the file yourself:

After creating your phyphox file you can share it with any service that allows you to transfer files. This can be via email, a service like WhatsApp or by sharing a link to services like Dropbox, Google Drive or OneDrive. If you have access to some webspace, you can even upload the file and just share a link to the file (which is probably the most reliable way).

If you see the file, but your device does not offer opening it in phyphox (either via “open” or via “share”), please let us know (email to staacks@physik.rwth-aachen.de). In many cases we cannot fix the problem, but we would still like to know about it. The problem is, that some apps try to open the file without telling the system the file extension “.phyphox” or telling the Android system a reasonable file type (since this is not a common file format, the phone cannot recognize it). Therefore, Android does not know that it should offer phyphox. A common example for this is the “My files” app by Samsung. The only alternative is that we let phyphox tell Android, that it could handle all file formats, but then Android would offer phyphox even if you just wanted to open a calendar entry and nobody would want that.

To avoid this type of problem we have added support to open phyphox-files from QR codes. These can either point to a phyphox file on the web or you can directly create them from within our editor.

By default every input and every analysis module just appends its output to the buffer attached to it. So, when “clear” is not set, your data will pile up through multiple iterations of the analysis process and the calculation results will appear multiple times. “Clear” allows you to delete the old data at certain points of the calculation and can only be set for the inputs and outputs of analysis modules.

If “clear” is enabled for an input, the data is read from the buffer at the input and then deleted. So, the data will be processed by this module, but it is not available any more for the next modules (careful if you still want to display it!) or in the next iteration of the analysis process. In most cases, you do not want this.

If “clear” is enabled for an output, the data in the output buffer is deleted and then the result from the module is written to this buffer. So the you are only working with fresh results and in most cases this is what you want in simple experiments.

No, phyphox is free to use by anybody without any conditions. Also, the source code for our app is open under the GNU GPL 3 licence.

We love to share and in principle we encourage that others reuse our work. However, in some cases, this can be complicated as not all images in the news section have been created by us. Also, the RWTH Aachen logo is subject to a more complicated licence and the name RWTH Aachen University is protected. On the other hand, our videos are uploaded to Youtube under a Creative Commons licence and we happily apply the same licence to our works if requested.

Therefore, in general, you can freely use the phyphox-logo (see below about using the name “phyphox”), screenshots from the app, the material supplied as press material at the bottom of the website and any part of our videos (under the terms of the Creative Commons Attribution licence). If you want to use something else, feel free to contact us. Chances are good that we just did not get around to stick a CC-label to it.

We have registered the name “phyphox” as a protected brand name. This means that you cannot simply use the name for some other product and take the name from us. But as long as you use the name phyphox to refer to us or our app, you can freely do so and you may also use our logo to do this (fair use). Just don’t pose as an author of our app or a member of our institute or university.

Of course you can. We are happy to see phyphox being used in scientific context, no matter if it is physics education, fundamental research, engineering or any other academic discipline. Let us know if you need some help as phyphox might be able to make your research easier than you expected by optimizing in-app data analysis or directly controlling the app from a computer via Python or a similar programming language.

If you just want to refer to phyphox in general, we would suggest our Physics Education paper (preprint on arxiv). Of course, for more specific features you might prefer a more specific paper.