Measurements

Accuracy: Measurement of the deviation of a spread of data with reference to the actual valuePrecision: Measurement of a spread of data from the average value/ Measurement of the reproducibility of results.Systematic Error: Repeating the measurement under the same conditions yields readings with error of the same magnitude and sign. E.g. zero errors, background radiation, parallax error etc. Can be eliminated completely by checking calibration and alignment of instruments.Random error: Repeating the measurement under the same conditions yields readings with error of different magnitude and sign. E.g. fluctuations, human reaction time, etc. Cannot be eliminated completely but can be minimized by averaging or plotting of graphs and drawing a best-fit line.To explain non-linear relationship: Gradient of graph decreases/increases as x-axis factor increases. Not possible to draw best-fit line hence non-linear.Differentiate between fundamental and derived units:- Fundamental units: Defines as the standard- Derived units: Expressed in terms of the fundamental unitsWhen calculating percentage uncertainty, no need to take into consideration constants in given equation.For addition and subtraction, take smallest significant figures.For multiplication and division, take largest significant figures.To be proportional, graph must be a straight line AND must pass through the origin!By increasing range in experiment, fractional error in measurement smaller, hence more accurate.Most nuclei have approximately the same density.An electron is 1000 times smaller than a proton.Mass of the universe is 1050kg.

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