20 IB Physics IA ideas with a smartphone

Each idea names an independent and a dependent variable and links to the FizziQ activity that gives the instrument and a base protocol.

A good internal assessment needs a measurable relationship, enough data points and a credible uncertainty analysis. A phone with the free FizziQ app gives you the instrument (accelerometer, microphone and spectrum analyzer, magnetometer, light sensor, barometer, video tracking), the data logging and the CSV export; the experiment notebook keeps graphs and calculations, and its statistics tools give standard deviations for the uncertainty section. Adapt the ranges to your own equipment and check the sensor's resolution first: the measurement uncertainty and sensor noise activities show how.

Waves

  1. Speed of sound against air temperature. Independent variable: air temperature (room, outdoors, heated tube). Dependent variable: speed of sound from two acoustic stopwatches. Base protocol: FizziQ activity.
  2. Resonant frequency of a tube against its length. Independent variable: tube length. Dependent variable: fundamental frequency on the spectrum analyzer. Base protocol: FizziQ activity.
  3. Helmholtz resonance against bottle volume. Independent variable: volume of air in the bottle. Dependent variable: resonance frequency. Base protocol: FizziQ activity.
  4. Doppler shift against source speed. Independent variable: speed of a moving sound source. Dependent variable: frequency shift. Base protocol: FizziQ activity.
  5. Sound level against distance. Independent variable: distance to a white-noise source. Dependent variable: sound level in dB. Base protocol: FizziQ activity.
  6. Beat frequency against frequency difference. Independent variable: difference between two tones. Dependent variable: beat frequency from the level trace. Base protocol: FizziQ activity.

Mechanics

  1. Coefficient of restitution against drop height or surface. Independent variable: drop height, or surface material. Dependent variable: time between bounces, hence e. Base protocol: FizziQ activity.
  2. Period of a mass-spring system against mass. Independent variable: added mass. Dependent variable: period from the accelerometer trace. Base protocol: FizziQ activity.
  3. Pendulum period against amplitude. Independent variable: release angle. Dependent variable: period, to test isochronism. Base protocol: FizziQ activity.
  4. Centripetal acceleration against angular velocity. Independent variable: rotation rate. Dependent variable: radial acceleration. Base protocol: FizziQ activity.
  5. Acceleration of an Atwood machine against mass difference. Independent variable: mass difference. Dependent variable: acceleration of the trolley. Base protocol: FizziQ activity.
  6. Rolling acceleration against incline angle and object shape. Independent variable: angle, or solid versus hollow cylinder. Dependent variable: linear and angular acceleration. Base protocol: FizziQ activity.
  7. Projectile range against launch angle (video). Independent variable: launch angle. Dependent variable: range from video tracking. Base protocol: FizziQ activity.
  8. Drag on a shuttlecock (video). Independent variable: initial speed. Dependent variable: deviation from a parabola. Base protocol: FizziQ activity.

Electromagnetism

  1. Magnetic field of a coil against current. Independent variable: current. Dependent variable: magnetic field from the magnetometer. Base protocol: FizziQ activity.
  2. Magnetic field against distance from a magnet. Independent variable: distance. Dependent variable: field magnitude. Base protocol: FizziQ activity.

Optics

  1. Illuminance against distance from a lamp. Independent variable: distance. Dependent variable: illuminance in lux, to test 1/r². Base protocol: FizziQ activity.
  2. Light transmission against number of absorbing layers. Independent variable: number of sheets. Dependent variable: transmitted illuminance (Beer-Lambert). Base protocol: FizziQ activity.

Thermal physics

  1. Pressure against temperature of a sealed gas. Independent variable: temperature of the jar. Dependent variable: pressure from the phone's barometer. Base protocol: FizziQ activity.
  2. Cooling or convection against heating power (external probes). Independent variable: heater power. Dependent variable: temperature at two heights. Base protocol: FizziQ activity.

Before you choose

  • Prefer a relationship with a known model (T² against m, 1/r², v = λf): the analysis section writes itself.
  • Plan at least five values of the independent variable and three repeats; FizziQ's multi-recording mode makes repeats cheap.
  • Record the phone model and the sampling rate of the sensor in your method; both affect the uncertainty.
  • Export the raw CSV and keep the notebook: examiners like to see the data, not just the graph.

Also see GCSE and A-level practicals with a smartphone and the experiments by sensor.