Twelve projects using indirect measurement methods.

How well does a linear or quadratic function model the conductivity of sodium chloride solutions derived from voltage and current measurements at constant temperature?

Raw data

Salt mass, solution volume, reference and sample voltage, current and temperature

Derived quantity

Concentration, resistance and conductivity

Mathematics

Calibration, model comparison, residual analysis and uncertainty propagation

Controls and limitations

Keep electrode geometry, temperature, measurement duration, electrode material, voltage and mixing constant. Low DC voltage and short measurement periods reduce electrochemical effects.

Suitable equipment

How do modelled discharge curves and numerically estimated delivered energy differ among battery types under the same resistive load?

Raw data

Voltage U(t), current I(t) and time

Derived quantity

Power P(t) = U(t)·I(t) and energy E = ∫U(t)I(t)dt

Mathematics

Regression, trapezoidal rule, residuals and model comparison

Controls and limitations

Use suitable low-voltage batteries and loads only; do not short-circuit cells. Document the load, sampling interval and stopping rule.

Suitable equipment

To what extent can a cosine model describe power as a function of a solar cell’s angle of incidence?

Raw data

Angle θ, voltage U(θ) and current I(θ)

Derived quantity

Power P(θ) = U(θ)·I(θ) and, if appropriate, integrated energy yield

Mathematics

Trigonometric regression, optimisation and analysis of model deviations

Controls and limitations

Control the light source, distance, shadows, orientation and measurement time.

Suitable equipment

How does container material affect the cooling constant obtained from temperature-time data for a drink?

Raw data

Temperature T(t), time and ambient temperature

Derived quantity

Cooling constant k and characteristic time

Mathematics

Exponential regression, half-life, residuals and parameter comparison

Controls and limitations

Keep volume, starting temperature, container geometry, sensor position and environment as constant as possible.

Suitable equipment

How do air-exchange rates obtained from exponential CO₂ decay models differ among ventilation strategies?

Raw data

CO₂ concentration C(t), time, temperature and ventilation state

Derived quantity

Decay constant and relative air-exchange rate

Mathematics

Exponential model, parameter comparison and sensitivity analysis

Controls and limitations

Do not deliberately build up CO₂ in poorly ventilated rooms. Document the initial value, outdoor value, room volume and window position.

Suitable equipment

How does the GPS position-error ellipse change between open ground, tree cover and dense buildings?

Raw data

Many coordinate pairs at one fixed location

Derived quantity

Local x/y deviations, covariance and an error ellipse

Mathematics

Coordinate transformation, covariance matrices, statistics and ellipse geometry

Controls and limitations

Use the same device, measurement duration and as comparable satellite conditions as possible.

Suitable equipment

How accurately can the speed of sound be determined from resonant frequencies in tubes of different lengths?

Raw data

Resonance frequency f, tube length L and possibly temperature

Derived quantity

Speed of sound v from the fitted slope

Mathematics

Regression of f against 1/L, slope interpretation and error analysis

Controls and limitations

Document microphone position, excitation method, tube diameter and room acoustics.

Suitable equipment

Which power model best describes the measured relative magnetic-field strength along the axis of a permanent magnet?

Raw data

Relative field strength B, distance d and background reading

Derived quantity

Exponent n and offset B₀ in B(d) = a·d⁻ⁿ + B₀

Mathematics

Non-linear regression or log-linearisation, residuals and uncertainty analysis

Controls and limitations

Keep orientation, measurement axis, zero point, background field and distance measurement consistent.

Suitable equipment

To what extent does the Torricelli model describe the water level in a draining container?

Raw data

Water height h(t), time, outlet geometry and container geometry

Derived quantity

Flow parameter k and the linearised quantity √h

Mathematics

Differential equations, linearisation, regression and goodness of fit

Controls and limitations

Secure the container and outlet; read water height from the same viewing angle.

Suitable equipment

How does the evaporation rate obtained from mass-time data change with fan voltage?

Raw data

Mass m(t), time, fan setting or voltage and temperature

Derived quantity

Evaporation rate −dm/dt and fitted constant

Mathematics

Linear, exponential or piecewise models and multiple regression

Controls and limitations

Document container surface area, liquid amount, fan distance and ambient conditions.

Suitable equipment

How well does a quadratic model describe the horizontal and vertical position data of a thrown ball?

Raw data

Pixel positions, frame numbers, frame rate and a length reference

Derived quantity

x(t), y(t), velocity and acceleration

Mathematics

Quadratic regression, derivatives, parameter comparison and perspective error

Controls and limitations

Fix the camera, keep the motion plane approximately parallel to the image sensor and place the scale reference in the same plane.

Suitable equipment

How does the area of a defined colour-threshold region change as dye spreads in still water?

Raw data

Image sequence, timestamps, scale and colour values

Derived quantity

Area, equivalent radius and spreading speed

Mathematics

Scaling, power or square-root models and regression

Controls and limitations

Keep camera position, lighting, water volume, drop size and colour threshold constant.

Suitable equipment