Accuracy How close the value of the measurement to the actual value www.myfunphysicsworld.blogspot.com
ConsistencyThe consistency of a measuringinstrument is its ability toregister the same readingwhen a measurement isrepeated. www.myfunphysicsworld.blogspot.com
Sensitivity The instruments ability to detect a small change in the quantity to be measured Responds faster, by a larger extend to small variations in quantity measured www.myfunphysicsworld.blogspot.com
READINGS Deviation 1 0.5 0.08 2 0.4 0.02 3 0.5 0.08 4 0.3 0.12 5 0.4 0.02Average 0.42 0.064 = 0.06 RELATIVE DEVIATION : = average deviation x 100% average = 0.06/0.42 x 100% = 14.29 % www.myfunphysicsworld.blogspot.com
4amanah until here20/01 www.myfunphysicsworld.blogspot.com
The consistency of a measuring instrument can be improved by:(a) eliminating parallax measurement.(b) exercising greater care and effort when taking readings.(c) using an instrument which is not defective www.myfunphysicsworld.blogspot.com
Systematics errors Due to1. the error in calibration of instrument which makes it defective2. Zero error* of the instrument Zero error – the pointer of the instrument does not return to zero when not in use www.myfunphysicsworld.blogspot.com
Systematics errors Will lead to a decrease in accuracy Always occur with the same value when we measure using the same instrument in the same way Readings taken are always larger or always smaller than the true value www.myfunphysicsworld.blogspot.com
Can we eliminate thesystematic error by repeatingthe measurement andaveraging out the result? No! Cannot! Only can by: calibrating or doing adjustment to the instrument www.myfunphysicsworld.blogspot.com
Random errors www.myfunphysicsworld.blogspot.com
Random errors Due to1. the carelessness of the observer when making measurement (parallax error)2. Sudden change of ambient factor (temperature, air circulation) Will lead to a decrease in consistency www.myfunphysicsworld.blogspot.com
Zero Error = +0.04 mm Correct reading meaning that 0.04 mm Micrometer reading -(+0.04) must be = Micrometer reading - 0.04 substracted from all www.myfunphysicsworld.blogspot.com readings taken.
Zero Error = -0.03 mm Correct reading meaning that 0.03 mm Micrometer reading - (-0.03) must be = Micrometer reading + 0.03 added to all readings www.myfunphysicsworld.blogspot.com taken.
Figure shows a micrometer screw gauge used to measure the size of an object. Determine the size of the object if the micrometer has a zero (a) +0.01 mm (b) -0.03 mm www.myfunphysicsworld.blogspot.com
Solution The reading of the gauge = 4.50 + 0.21 = 4.71 mm (a) Size of object =Reading- Zero Erro = 4.71 – (+0.01) = 4.70 mm (b) Size of object = Reading – Zero Error = 4.71-(-0.03) = 4.74 mm www.myfunphysicsworld.blogspot.com