Q1. (a) In the context of measurement and instrumentation, define: - Sensitivity
ID: 2085163 • Letter: Q
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Q1. (a) In the context of measurement and instrumentation, define: - Sensitivity - Accuracy -Systematic error - Random error 20% (b) An instrument to measure force is initially calibrated after manufacture to generate an output voltage of 4.0 V at 6 N and-3.0 V at -6 N. Assume that the instrument behaves linearly - Using graph paper provided, draw a graph of the variation in output voltage, as a function of the input force in the range of input pressures -8 to +16 N for this initial calibration data. Label all axes correctly. Calculate the sensitivity of the instrument to pressure. - State the values of the output offset of the instrument. After 1 year, the performance of the instrument is recalibrated, and the values in Table Q1B are obtained: Force (N) -8 Output Voltage (V -8 0 12 16 12 16 Table Q1B Using the same graph as before, plot the after 1 year data in Table Q1B. Make sure you clearly identify the initial calibration data and the after 1 year data in your graph. -Identify the dominant source of error now evident in the instrument Explain your reasoning - State the secondary source of error now evident in the instrument Explain your reasoning. 30%Explanation / Answer
1(a)
Sensitivity
Sensitivity is the smallest amount of difference in quantity that will change an instrument's reading.
Accuracy
Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.
Systematic Error
Systematic error is predictable and typically constant or proportional to the true value. If the cause of the systematic error can be identified, then it usually can be eliminated. Systematic errors are caused by imperfect calibration of measurement instruments or imperfect methods of observation, or interference of the environment with the measurement process, and always affect the results of an experiment in a predictable direction. Incorrect zeroing of an instrument leading to a zero error is an example of systematic error in instrumentation.
Random Error
Random error is always present in a measurement. It is caused by inherently unpredictable fluctuations in the readings of a measurement apparatus or in the experimenter's interpretation of the instrumental reading. Random errors show up as different results for ostensibly the same repeated measurement. They can be estimated by comparing multiple measurements, and reduced by averaging multiple measurements.
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