Identifying apparatus — matching the right instrument to what you're measuring, based on its resolution and range.
Calibrating instruments — checking an instrument against a known value so its readings are accurate, and using calibration curves for non-linear sensors.
Measuring variables — choosing the correct instrument for length, mass, time, temperature, p.d., current, angle, and frequency.
Control variables & fair tests — independent, dependent, and controlled variables, and why only ONE thing should ever change on purpose.
Repeat readings — why we repeat, how it improves reliability, and when repeating isn't actually practical.
Health & safety — the standard precautions examiners expect for masses, wires, springs, circuits, and general lab conduct.
Data collection — standard form, significant figures, mean values, and turning equations into straight-line graphs (y = mx + c).
Before you can plan any experiment, you need to ask: "What am I actually measuring, and what tool measures that?"
Every physical quantity — length, mass, time, angle, current — has a standard instrument that goes with it.
Think of apparatus selection like picking the right kitchen tool: you wouldn't use a tablespoon to measure a
teaspoon of salt, and you wouldn't use a metre ruler to measure the diameter of a human hair.
The apparatus you need falls into two categories:
- What you are measuring — e.g. the block of metal, the wire, the beaker of liquid.
- How you are measuring it — e.g. the ruler, the thermometer, the ammeter.
Common Apparatus & What They Measure
| Apparatus | Measures |
|---|
| Metre ruler | Distance / length (1 cm – 1 m) |
| Vernier calipers | Short lengths (0.1 mm – 1 cm) |
| Micrometer screw gauge | Very short lengths (0.01 mm – 0.1 mm) |
| Top-pan balance | Mass |
| Protractor | Angles |
| Stopwatch | Time |
| Ammeter | Current |
| Voltmeter | Potential difference (p.d.) |
| Thermometer | Temperature |
| Oscilloscope | Waves / frequency |
Quick Rule for Length
A few cm – 1 m →
metre ruler. Between 0.1 mm – a few cm →
vernier calipers.
Between 0.01 mm – 0.1 mm →
micrometer screw gauge.
Worked Example: Specific Heat Capacity Setup
To measure the specific heat capacity of an aluminium block, you'd need:
- An aluminium block (ideally 1 kg) or a beaker of fluid with known mass
- A thermometer (to measure temperature rise)
- An immersion heater (to supply heat)
- A power source, plus a voltmeter, ammeter, and stopwatch (or a joulemeter)
- Wires and connectors
Notice how the list includes even the "boring" parts — wires and connectors. Examiners want you to think
of the entire circuit, not just the star apparatus.