International A Level (IAL)PhysicsEdexcelRevision Notes3. Practical Skills in Physics IPractical Skills I: PlanningRange & Resolution of Instruments

Range & Resolution of Instruments (Edexcel International A Level (IAL) Physics): Revision Note

Exam code: YPH11

Written by: Katie M

Reviewed by: Caroline Carroll

Updated on 5 October 2026

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Range & Resolution of Instruments

All instruments have a range and resolution
- The range is the highest and lowest value an instrument can measure
- The resolution is the smallest increment an instrument can measure

Examples of resolutions for instruments are:

Experimental Instrument	Typical Resolution	Typical Range
Metre ruler	1 mm	0 – 1 m
Vernier Calipers	0.1 mm	0 – 300 mm
Micrometer Screw Gauge	0.01 mm	0 – 25 mm
Top-pan Balance	0.01 g	0 – 1 kg
Protractor	1°	0 – 180°
Stopwatch	0.01 s	0 – 9 hours 59 mins 59.99 seconds
Thermometer	1 °C	–10 °C – 110 °C
Voltmeter	1 mV – 0.1 V	0 – 1000 V
Ammeter	1 mA – 0.1 A	0 – 10 A
Oscilloscope	1 Hz	0 – 200 MHz

These are just examples of ranges and resolutions for these devices
- For example, some multimeters may have a bigger or smaller range depending on their model

The uncertainty in a single reading is ± half the resolution, for digital and analogue instruments alike
- For a digital device, such as a balance with a resolution of 0.001 kg, the uncertainty is ± 0.0005 kg
- For an analogue device, such as a thermometer, ruler or pan balance, the uncertainty is also ± half the resolution
- This is because when reading between the millimetre scale, the measurement will be rounded up or down by eye from the midpoint at 0.5 mm

Worked Example

Two digital thermometers display a reading in °C.

Thermometer 1: 80.13 °C

Thermometer 2: 42.0 °C

Which thermometer has the better resolution?

Answer:

The resolution is given by the smallest increment that the thermometer can read
- For thermometer 1 this is 0.01 °C
- For thermometer 2 this is 0.1 °C
Therefore, thermometer 1 has the better resolution

Examiner Tips and Tricks

Exam questions can refer to different instruments with various ranges and resolutions, for example, ammeters with a resolution of 0.2 mA instead.

Always use the information provided in the question, and look carefully at the scales. Never blindly assume the resolution of a piece of equipment given in an exam question.

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