Plan the investigation before moving a control
Write the relationship you want to investigate. Then identify the independent variable you change, the dependent variable you measure and the conditions you hold fixed. Keep the units with every reading.
For example, to investigate current against voltage, change voltage while keeping resistance fixed. If you change both at once, your observations no longer isolate the effect of voltage.
Ohm’s law: compare current at a fixed resistance
For an ohmic resistor under constant physical conditions, voltage V, current I and resistance R are related by V = IR. A virtual model can hold resistance constant so you can examine the relationship directly.
I = V ÷ R
With resistance fixed at 100 Ω, a voltage of 6 V gives a theoretical current of 0.06 A. Increasing voltage to 12 V gives 0.12 A. Doubling the voltage doubles the current in this model.
| Voltage | Resistance | Current |
|---|---|---|
| 3 V | 100 Ω | 0.03 A |
| 6 V | 100 Ω | 0.06 A |
| 12 V | 100 Ω | 0.12 A |
Plot voltage on one axis and current on the other. If voltage is plotted vertically against current horizontally, the slope represents resistance. Always label the axes before interpreting a gradient.
A real component may heat up or behave differently from an ideal ohmic resistor. A perfectly straight simulated plot is evidence about the assumptions of the model, not proof that every physical component is ohmic.
Simple pendulum: test the effect of length
For a small-angle ideal pendulum, the period T is the time for one complete oscillation. The model uses pendulum length L and gravitational acceleration g.
T = 2π √(L ÷ g)
Taking g = 9.81 m/s², a length of 1 m gives a theoretical period of about 2.01 s. At 4 m, the period is about 4.01 s. Quadrupling the length doubles the period because the relationship involves a square root.
State the model conditions: a small starting angle, a light string, a concentrated bob and negligible damping. When comparing runs, keep the starting angle and gravity the same. In a physical experiment, timing several oscillations and dividing by their count can reduce the effect of reaction time.
Check your prediction: does doubling length double the period?
No. In this ideal model, the period increases by √2, approximately 1.41 times. You would need four times the length to double the period.
Write an observation that someone else can understand
A useful record includes the question, settings, variable held constant, measured or calculated readings, units and a short conclusion. Identify whether the results came from a simulation or physical equipment.
Separate the observation from the explanation. “The current doubled” records a result; “resistance was fixed, so current was proportional to voltage” interprets it. Add one condition under which that explanation may not hold.
The NEUYI Science beta includes Ohm’s law, a simple pendulum, Hooke’s law and convex-lens investigations among its foundational models. Open the lab to check the current controls, learning modes and available notebook options.
References and further reading
The tables above are calculated examples, not readings captured from the NEUYI app or a physical apparatus. Virtual experiments complement supervised practical work.