Class 11 physics revision notes chapter 2 units and measurement is carefully designed by subject experts who have provided the definition of all the physical quantities used to represent data. Whether it could be while measuring length, mass, or speed etc. They would be prone to all the dimensional formulas of physical quantities used in physics. They would be witnessing range and order of time intervals of various phenomenon such as travel time for light from the nearest star. They would also be knowing the range and order to masses of electron and positron etc. and will get to learn about the relative error, percentage and absolute error etc.