Cooling curve of a pure substance sim
Melt stearic acid (or paraffin wax) in a hot water bath, drag the boiling tube into an air jacket, click the stopwatch on 30 s at a time and read the thermometer at eye level; your readings make a cooling curve with a flat part at the freezing point, which you read off and explain (the wax, a mixture, has none).
Thermal properties of matter: melting, freezing and latent heat · covers the O-Level, IGCSE, GCSE topic
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
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Free guide: 12 practicals as sims, and how to run one in a lesson →
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More physics sims
- Black-body radiation: temperature and colour simTurn up the supply to a lamp and watch its filament go from giving out only infrared to dull red, orange, yellow and yellowish white while its emission curve's peak moves to shorter wavelengths and its total power climbs; then warm a black or shiny can in a lamp's light until it absorbs as fast as it gives out, and see the same balance set the Earth's temperature.
- Charge flow and current simClose the switch on a real series loop and watch the lamp light at once while every ammeter reads the same; drag a magnifier over any lead to see the electrons drift from − to + against the conventional current, time a run, work out Q = I × t yourself (✗ reasons for mA and ms) and check it against a coulomb counter.
- Combining resistors simDrag real resistors into the clips of a resistance board to wire them in series or in parallel, measure V and I with real digital meters, work out R = V ÷ I from your own readings and check it against the series and parallel formulas, and see that adding a parallel branch lowers the total while adding in series raises it.
- Efficiency: a motor lifting a load simSet the supply's voltage and the load, then time a small geared motor winding a slotted-mass load up beside a half-metre rule: read the energy in from a joulemeter (or V × I × t), work out the useful energy m g Δh and the efficiency, watch a Sankey diagram of where the energy went draw itself, and plot how the efficiency changes with the load.
- Electric field patterns simSwitch on an EHT supply joined to electrodes in a dish of castor oil and watch semolina grains line up into the field pattern of a point, a charged sphere, two points or two parallel plates; drag the electrodes, show field lines running from + to −, and drop in a small + or − test charge to see the force on it.
- Energy resources: power a town simDrag the faders on a model town's control desk to switch on coal, gas, nuclear, biofuel, geothermal, hydroelectric, wind, solar and tidal power, change the wind, the sky and the hour, and see hour by hour whether the supply meets the town's demand, with scores for hours met, CO₂, renewables and rough cost; save your mixes to a table and sort the resources by renewable, from the Sun and available at any hour.