Errors & Uncertainties - Practical Work
__Random errors cause unpredictable fluctuations in an instrument’s readings because of uncontrollable factors, such as human errors or environmental conditions.
Affects the precision of results, causing a wider spread of values about the mean value.
Can be reduced by taking multiple repeat measurements, calculating an average, and drawing a graph to find the trend
__Systematic errors arise due to faulty equipment/instruments. This type of error is repeated every time the instrument is used, or the method is followed, which affects accuracy.
Cannot be reduced by taking more repeat measurements as the error is consistent with every repeat.
To reduce systematic errors, you need to make sure the equipment/instrument is calibrated to the true value.
Common systematic errors: zero error. Zero Error is when the equipment/instrument does not read 0 when the true value of the reading is 0.
__The precision of a measurement is how close the measured values are to each other; if a measurement is repeated several times, then they can be described as precise when the values are very similar to, or the same as, each other.
Measurements to a greater number of decimal places are said to be more precise than those to a whole number
Accuracy is how close the measured values are to the real/true value. Accuracy can be increased by repeating measurements, finding the mean, and drawing a graph to find the trend.
__There is always a degree of uncertainty when measurements are taken; the uncertainty can be thought of as the difference between the actual reading taken (caused by the equipment or techniques used) and the true value.
Absolute Uncertainty: uncertainty given as a fixed rational quantity (usually 1 significant figure)
Fractional Uncertainty: uncertainty given as a fraction of the measurement
Percentage Uncertainty: uncertainty given as a percentage of the measurement (usually given to 2 significant figures)
Calculating absolute uncertainties of Log() values:
When adding/subtracting values of measurement: add the absolute uncertainty
When multiplying/dividing values of measurement: add the percentage uncertainty
When the uncertainty is raised to a power: multiply the uncertainty by the value of the power
__Random errors cause unpredictable fluctuations in an instrument’s readings because of uncontrollable factors, such as human errors or environmental conditions.
Affects the precision of results, causing a wider spread of values about the mean value.
Can be reduced by taking multiple repeat measurements, calculating an average, and drawing a graph to find the trend
__Systematic errors arise due to faulty equipment/instruments. This type of error is repeated every time the instrument is used, or the method is followed, which affects accuracy.
Cannot be reduced by taking more repeat measurements as the error is consistent with every repeat.
To reduce systematic errors, you need to make sure the equipment/instrument is calibrated to the true value.
Common systematic errors: zero error. Zero Error is when the equipment/instrument does not read 0 when the true value of the reading is 0.
__The precision of a measurement is how close the measured values are to each other; if a measurement is repeated several times, then they can be described as precise when the values are very similar to, or the same as, each other.
Measurements to a greater number of decimal places are said to be more precise than those to a whole number
Accuracy is how close the measured values are to the real/true value. Accuracy can be increased by repeating measurements, finding the mean, and drawing a graph to find the trend.
__There is always a degree of uncertainty when measurements are taken; the uncertainty can be thought of as the difference between the actual reading taken (caused by the equipment or techniques used) and the true value.
Absolute Uncertainty: uncertainty given as a fixed rational quantity (usually 1 significant figure)
Fractional Uncertainty: uncertainty given as a fraction of the measurement
Percentage Uncertainty: uncertainty given as a percentage of the measurement (usually given to 2 significant figures)
Calculating absolute uncertainties of Log() values:
When adding/subtracting values of measurement: add the absolute uncertainty
When multiplying/dividing values of measurement: add the percentage uncertainty
When the uncertainty is raised to a power: multiply the uncertainty by the value of the power