Errors in measurements:-

My grandmother used to says that when we measure our height by standing vertically and by sleeping horizontally it’s changes ….it this true??? . When I did this practically …it happend.. Is this a magic .??? Not actually !!!!

It’s just a mistake done by me…. While observing and calculating.

Similarly,. Physics is a science based on observation and experiments. Obervation of physical quantities are made during an experiment. While observing and calculating…..,.( physical quantities ). For example during the atmosphere study we measure atmosphere pressure, wind velocity, humanity,ect. … All the measurement may be accurate, meaning that the measured values are the same as the true values. Accuracy is how close a measurements is to the actual value of that quantity. These measurements may be precise, meaning that multiple measurements give nearly identical values(ie.., reproducible result) . In actual measurements, an observation should may be both precise or neither accurate nor precise. The goal of the observer should be to get accurate as well as precise measurements.

Faulty measurements of physical quantity can lead to errors. The errors are broadly divided into the following two categories.

• Systematic errors:- systematic errors are errors that are not determined by chance but are introduced by an inaccuracy. Systematic errors such as Instrumental error,Error due to imperfection in experimental technique, personal error.
• Random error:- These are the error which are introduced even after following all the procedures to minimize systematic error.These type of error may be positive or negative . These error can not be eliminated completely but we can minimize them by repeated observations and then taking their mean(average).

To find error following steps are followed

• Arithmetic mean (of observed reading)
• Absolute error
• Mean absolute error
• Relative error
• Percentage error

Absolute error :- The magnitude of the difference between mean value and each individual value is called absolute error.

Mean absolute error:- The arithmetic mean of all the absolute error mean absolute error

Relative error:- The ratio of mean absolute error to the arithmetic mean value is called relative error

Percentage error:- when relative error is represented as percentage it is called percentage error.