1) A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it? A) A meter scale B) Avernier calliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and main scale has 10 divisions in 1 cm. C) A screw gauge having 100 divisions in the circular scale and pitch as 1 mm. D) A screw gauge having 50 divisions in the circular scale and pitch as 1 mm Answer: Option BExplanation:If student measures 3.50 cm. it means that there is an uncertanily of order 0.01cm. For vernier scale with 1MSD=1mm and 9MSD=10VSD LC of vernier caliper =1 MSD-1VSD = 110(1−910) = 1100 cm
