Problems 1.1. Find the area of a rectangular plate having length (21.3 ± 0.2)cm and width (9.80 ± 0.10)cm.
Solution:
Data:
L = 21.3cm,
w = 9.80cm
where ΔL = 0.2cm and Δw = 0.10cm are the least counts of the instruments.
Area of rectangular plate = length x width
A=Lxw=213x9.80=208.74
The least number of significant figures in numerical is 3, so we can round off the answer to
3 significant figures:
A = 209cm²
Error calculation (least count) can be calculated as:
ΔA/A = ΔL/L = Δw/w
ΔA/209 = ΔL/21.3 = Δw/9.8 => ΔA = 4.09 = 4 (round off to 1 significant figure)
A = 209 + 4cm² Ans.
