Question

Thickness of a pencil measured by using a screw gauge(least count.001 cm) comes out to be 0.802cm. The percentage error in the measurement is

Answer 1

Given that:

Thickness t=0.802cm

Least count=0.001 cm
now error in measuring t=(0.802+-0.001)
%age error=0.001/0.802×100%
=0.125%

Answer 2

The percentage error is 0.125%  

Given:  

Pencil thickness = 0.802 cm  

Solution:  

The percentage error is calculated based on the least count which remains constant for every measurement for the instrument.  

Least count of screw gauge is given as 0.001 cm.  

The error will be thickness,

$t=0.802 \pm 0.001$

$\Delta t$ is given as 0.001 cm

Thereby,

$Percentage \ error =\frac{\Delta t}{t} \times 100 \%$

$Percentage \ error =\frac{0.001}{0.802} \times 100 \%$

$\therefore Percentage \ error = 0.125 \%$