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The smallest change in a quantity that a measuring instrument can show.

The smallest change that a measuring instrument can show.

The instrument needs both a sufficient range and a suitable resolution. A short ruler would be inconvenient for measuring a running course, whereas a trundle wheel would be too coarse for measuring a small card. Place the zero mark at the chosen starting point and view a scale straight on to reduce parallax error.

Choose apparatus for the size of the quantity: a ruler may suit a long length, but callipers give better resolution for a small diameter.

Justify an instrument rather than merely naming it: state that its range includes the expected values and that its resolution is fine enough for the required measurement.

The smallest change in a quantity that a measuring instrument can detect or display.

Can it distinguish changes that matter? Its resolution must be fine enough. A ruler marked every millimetre is more suitable than one marked only every centimetre if small changes in length must be detected.

Resolution

Definition

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OCR GCSE Physics A · J249

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