The document defines error as the difference between the true value and measured value of a quantity. It provides examples of errors in measuring weight and time. Random errors can occur due to human imperfections and natural variations, and are reduced by taking the average of multiple measurements. The document also contains examples of random errors in measuring resistance and length using the same instruments.

2. Defination:Error: Difference between marked value/true value and
measured value.
e.g. Marked value= 80.00 Kg measured value = 81 Kg error= 01 Kg
ERROR AND UNCERTAINY

3. For example measurement of time have
uncertainity due to human natural imperfection and
reaction time and variation of natural process.

4. Its cause is unknown e.g. measurement of a resistance with same apparatus in morning
is 2Ω and in evening is 3Ω.
e.g. length of a stick measured by three students with same meter rod are
i) 2.1 m ii) 2.2 m iii) 2.3 of Random error:
Random error is reduced/eliminated by taking average of a number of readings.
Reduction of Random error:

6. Summery

7. good luck:
Be blessed see u again
Professor Asif Mahood
Faculty of physics
Pgc gujranwala