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Your Smartphone is a Science Lab: 50 Physics Measures you can do with your mobile

Updated: Aug 2, 2023

Can you imagine that your smartphone can do more than 50 different types of measurements on sound, movement, light, color, energy?


All of this is possible thanks to the microscopic sized sensors that are in your smartphone.


With FizziQ, we provide access to most of these sensors to be able to make precision measurements with your smartphone or tablet. Everyone can use their smartphone to learn science!


Table of contents


Orientation (Compass)

The compass displays the angle of your phone with magnetic north.

This instrument uses the different data from the magnetometer to calculate this angle.

The accuracy of the data is less than 0.1 degrees and the data update rate is generally greater than 10 hertz, or 10 data per second.",


Brightness (Luxmeter)

The ambient light sensor measures the illuminance on a given surface. The measurement is expressed in lux. A lux is the illuminance of a surface which receives, in a uniformly distributed manner, a luminous flux of one lumen per square meter.

The lux is a generally little known unit. When we buy light bulbs, we more often look at the number of watts and the number of lumens. The full moon generates about one lux, a living room lamp, about 50 lux, the illumination of a classroom, just like sunrise or sunset, about 400 lux, indirect daylight, more than 10 000 lux, while direct sunlight generates over 30,000 lux.

The data update frequency depends on the sensors of your mobile and is generally higher than 10 hertz, or 10 data per second

Luminance (Luxmeter)

The smartphone camera makes it possible to calculate the luminance of the luminous flux which is emitted or reflected by the objects which are in its field. Luminance is proportional to light intensity but, unlike illuminance measurement, does not take into account the area of the light source. It is the visual feeling of light intensity.

The local luminance calculates the luminance of the central pixels of the image captured by the camera. Global luminance calculates the average luminance across all pixels in the camera image.

In FizziQ, the luminance is calculated as the average of the red, green and blue components detected by the smartphone camera over the whole image and related to the calibration value. The measurement is updated at a frequency of approximately 10 Hz.

WARNING: the luminance measurements are measurements relative to a reference that the user sets by pressing the CALIB button.

Colors (Colorimeter)

The colorimeter is a tool that analyzes colored samples. FizziQ uses the photographic detector present in your mobile to calculate different parameters that characterize the color reflected or transmitted by the objects you are analyzing.

Color is a physical phenomenon that is difficult to study. Everyone perceives colors differently. Cellphone photo sensors have different sensitivities at certain wavelengths and results are not always comparable for different cellphones.

The Color screen gives you a lot of information about the color of the center of the image: a sample of the color perceived by the sensor and its common name, the spectrum in % of the maximum value of the red, green and blue that make up that color, the hue on the HSV scale, and the intensity of that hue.

RGB color spectrum (Colorimeter)

The English scientist Thomas Young was the first to discover that three monochromatic colors, red, green and blue, suffice to obtain all sensations of color by addition. Our retina is also made up of detectors called cones which have specific sensitivities to each of these colors.

A digital camera works in a similar way. Attached to the sensor is a network of small red, green and blue color filters called a Bayer filter. This filter allows wavelengths around 460 nm (blue), 550 nm (green) and 640 nm (red) to pass.

Your laptop makes many adjustments to ensure that the image is always clear and colors are well represented, but this may affect your measurements if you compare different colors. It is therefore recommended to press the Expo button to fix the parameters of your device when you want to compare different colors.​

Absorbance (Colorimeter)

Absorbance measures the ability of a medium to absorb light passing through it. This measurement is used in spectrometry to measure the concentrations of chemicals. The absorbance is the decimal logarithm of the ratio between the reference light intensity and the transmitted light intensity.

Absorbance is a dimensionless relative data. The meter should be calibrated using the CAL button, which will set the reference light intensity. The Reset button cancels the calibration.

Your smartphone can't compare to a laboratory spectrometer that allows you to perform high-precision measurements, but it still allows you to perform some exciting experiments on light.",


Number of steps (Pedometer)

The pedometer is an instrument that measures the number of steps you take

This calculation is made using data from the accelerometer which indicates when your movements seem to be regular enough to indicate that you are walking. By analyzing changes in your body's acceleration, the pedometer is able to identify when you take a step.

The pedometer only starts when it detects a regularity in your walking movement. For this reason, you must first walk at least 7 steps before it starts counting your steps.

The precision of this instrument depends on the length of your route but it is usually one step for every hundred steps.


Vertical inclination (Inclinometer)

One of the oldest measuring tools used by early architects is the plumb line. This instrument allowed to know if a wall was vertical and was very important to build strong buildings.

The inclinometer of your smartphone has the same function and allows you to calculate the angle of your mobile in relation to the vertical.

The angle you measure is the angle between the line that goes through the longest side of your smartphone and the vertical.

The precision of this instrument is 0.1 degree and the update rate is the same as that of the accelerometer, that is to say less than 10 milliseconds.


Horizontal inclination (Inclinometer)

Everyone knows the spirit level that lets you know if a table is horizontal.

The inclinometer of your smartphone has the same function and allows you to calculate the angle of your mobile in relation to a horizontal plane.

The angle you measure is the angle between the surface of the smartphone and the horizontal plane.

The precision of this instrument is 0.1 degree and the update rate is the same as that of the accelerometer, that is to say less than 10 milliseconds.

Linear Acceleration (Accelerometer)

Linear acceleration measures the variation in speed of your mobile (in the terrestrial frame of reference) along the three axes X, Y and Z. It is measured in m/s². The value is therefore zero (along all axes) when the telephone is stationary.

This measurement is in fact the combined result of two measurements: absolute absolute acceleration, also called acceleration with g, and weightlessness which is given by the magnetometer. This subtracts the gravity component from the measurement. Linear acceleration is thus a measurement that only reflects the acceleration created by the user without gravity, as if you were in weightlessness! This measurement is very useful for games where only the movement of the user matters.

The accelerometer measures the intensity of all the forces exerted on your mobile and expresses them in the form of an acceleration. If you shake your mobile and therefore apply forces to it, you will see the measurement increase or decrease rapidly.

Your smartphone's accelerometer is very accurate. The accuracy of the measurements is less than 0.01 m/s², and the data update frequency is greater than 100 hertz, that is, 100 data are calculated per second.

Absolute Acceleration (Accelerometer)

Absolute acceleration measures the acceleration produced by all the forces acting on the laptop. If you keep your laptop stationary, you will find that the accelerometer displays a value of approximately 9.8 m/s². This acceleration results from the force you exert to keep your mobile stationary and counter the force of weightlessness.

The absolute acceleration is the data directly produced by the accelerometer sensor, and is in this sense more precise than the linear acceleration which is the result of two sensors.

Your smartphone's accelerometer is very accurate. The accuracy of the measurements is less than 0.01 m/s², and the data update frequency is greater than 100 hertz, that is, 100 data are calculated per second.

Sound volume (Microphone)

The sound level meter measures the volume of sound picked up by the microphone. It is expressed in decibels, or dB.

The decibel scale is logarithmic: a 40 dB source is 100 times more intense than a 20 dB source. The quietest sound that a human ear can perceive is zero decibels. Ordinary conversation reaches around 60 dB, the sound of a mixer is often 90 dB, and sounds above 140 dB are painful to the human ear. Continuous exposure to sounds over 90 dB can cause hearing loss.

The data update rate is greater than 250 hertz, i.e. 250 measurements per second.

Smartphones have more or less sensitive microphones, and the volume measurement will vary from one to another. The software calibrates the device so that the loudest sound observed over a period of time is 90 dB and the weakest is 20 dB. It therefore produces a measure of the relative loudness of the sound rather than an absolute measure.

Oscillogram (Microphone)

An oscillogram gives a temporal representation of a signal by measuring the variations of its intensity (or amplitude) over time.

Both periodic and non-periodic signals can be represented by an oscillogram, but only those that exhibit periodicity will have a stable representation over time.

Noticed

To create the oscillogram, your smartphone records the signal over small time intervals, then synchronizes these recordings so as to always start the sequence at the same place in it. For example, he can start the sequence when the maximum is reached.

The waveform timescale is 10 milliseconds. The amplitude is expressed as a percentage of the maximum amplitude that the microphone is able to detect.

Fundamental Frequency (Microphone)

The frequency of a signal corresponds to the number of repetitions per second of the elementary pattern that composes it. It is expressed in hertz, noted Hz.

A sound is generally composed of several pure tones having different frequencies. The frequency counter gives the frequency of strongest intensity among all the frequencies which compose it: the dominant frequency.

Noticed

To calculate this frequency, the frequency counter records the sound from the microphone over small time intervals. Then, using a mathematical process called the Fourier transform, it calculates the frequencies of all pure sounds and the loudness of those sounds. It then deduces the dominant sound, which is the frequency with the strongest sound intensity.

It is expected that a future version will systematically give the frequency of the fundamental in order not to have (sometimes) the frequency of the harmonic of greater amplitude. When this modification will be effective, we will indicate it in the information of the sensor on the application. We will then integrate a new measuring instrument to display the "note" heard since this note depends directly on the fundamental frequency (for example, an A4 corresponds to a fundamental frequency of 440 Hz)

Frequency Spectrum (Microphone)

Unlike the frequency meter which only gives the dominant frequency of a sound (or that of its fundamental depending on the version), the sound spectrum details all the frequencies that make it up. This tool thus makes it possible to precisely describe the characteristics of a sound.

The greater the number of frequencies that make up the note, the more the sound is said to be “rich”. This contributes to the “timbre” of an instrument.

Noticed

The frequencies are expressed in hertz, noted Hz. The amplitude is expressed as a percentage of the maximum amplitude that the microphone is capable of detecting.

Accuracy

Data is refreshed every 0.5 seconds.

Magnetic field (Magnetometer)

The magnetometer calculates the global magnetic field to which your mobile is subjected. The measurement is expressed in microTesla, noted μT.

Noticed

Your phone's magnetometer is very sensitive to electrical currents and metallic objects. Metal detectors use magnetometers. Of course, your magnetometer also detects the Earth's magnetic field which varies between 20 and 80 μT depending on the location.

Accuracy

The sensitivity of magnetometers contained in smartphones is generally less than 0.2 μT. The data update rate is mostly above 50 hertz, or 50 data per second.

Rotation Speed (Gyroscope)

A gyroscope is an instrument that measures the orientation of an object in space.

Rotation speed is measured in rpm, which is the number of revolutions per minute.

The rotation of your mobile can be measured in relation to the 3 axes of your phone (X, Y and Z)

Your smartphone has gyroscopes that allow you to determine the rotation speed of the mobile on itself in all directions. This is very useful for games for example when you use your phone to control a car or a character.

Face rotation is the rotation of your mobile relative to the z axis, which is perpendicular to the face of the smartphone. Longitudinal rotation is the rotation around the y axis which is the length of your laptop. If you put your mobile in a cylinder, you can use this sensor to detect if your mobile is moving and at what speed

Noticed

Your smartphone has gyroscopes that allow you to determine the rotation speed of the mobile on itself in all directions. This is very useful for games for example when you use your phone to control a car or a character.

Gyroscopes are essential for the navigation of airplanes or satellites and allows them to detect whether they are pointing up, down or sideways. Usually, a gyroscope consists of a wheel or disk that spins around another disk or axis. The rotation of the disks measures both the orientation of the gyroscope itself and the speed at which it spins in one direction or the other.

If you put your mobile in a cylinder, you can use this sensor to detect if your mobile is moving and at what speed

Latitude/longitude (G.P.S)

GPS allows you to calculate the position of your mobile on Earth. A point on the earth's surface is characterized by its latitude and longitude.

Latitude: Latitude is the angle formed between the vertical of a place and the plane of the equator: from + 90 degrees north towards the North Pole to - 90 degrees towards the South Pole.

FizziQ expresses latitude in millidegrees (1 millidegree = 0.001 degree).

Longitude: Longitude is the angular value of the east-west position of a point with respect to the reference longitude on Earth, the Greenwich meridian. FizziQ expresses longitude in millidegrees.

Data is updated every second. The accuracy of the GPS for the position is usually about ten meters.

Speed (G.P.S)

GPS By analyzing the changes in this position, your smartphone deduces the speed of your smartphone. The accuracy of this instrument for speed measurement is generally less than 1 m/s.

Data is updated every second. The speed measurement usually takes a few seconds to be accurate because it is inferred from latitude and longitude measurements over a period of time.

Altitude (G.P.S)

The GPS allows you to calculate the position of your mobile on the earth. The system is also able to give the altitude above sea level at which your mobile is located.

Data is updated every second. The accuracy of the GPS for the position is usually about ten meters.

Accuracy (G.P.S)

In this measuring device, the accuracy display has been integrated. You can therefore display the accuracy of your GPS measurement by using the Accuracy instrument.

This precision gives a measure of the margin of error of your GPS. It is expressed in meters. An Accuracy of 10 meters indicates that the position of your smartphone is accurate to within 10 meters.

The GPS system works by receiving information from satellites that orbit the earth. For the accuracy to be optimal, the GPS must receive information from at least four satellites. The signal has difficulty passing through obstacles such as walls or trees. To improve the accuracy of your measurements, make sure you are on open ground with no obstacles between you and the sky.


Azimuth (Theodolite)

A theodolite is an optical measuring instrument used to measure horizontal and vertical angles with high precision. The azimuth is the angle between the target point in the theodolite's sight and magnetic north. This instrument is frequently used for triangulation calculations.

The azimuth accuracy is 1 degree and the measurements are made with a frequency of 50 hertz.


Elevation Angle (Theodolite)

​The elevation angle gives a measure of the angle between the horizontal and the target point in the sight of the theodolite. This instrument makes it possible to calculate the height of buildings, for example. This angle is positive if the sight is above the horizon and negative otherwise. It is expressed in degrees.

The accuracy of the elevation angle is 1 degree and the measurements are made with a frequency of 50 hertz.


Kinematics (Tools)

The purpose of kinematic analysis is to analyze the trajectory of a body from images taken at regular intervals, either in the form of chronophotographs or videos. The FizziQ kinematics module makes it possible to calculate from these two types of sequence the position of the bodies, the speed, the acceleration and their energy.


The presence of a camera allowing quality and slow-motion videos offers enormous possibilities of analysis for the students. Exciting protocols are available for all levels: https://www.fizziq.org/sports-cinematique






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