Question

A digital timer with eight readout is stated to have accuracy of 0.005 percent of reading, ±1  in the final digit. Readout is in s, ms and μs. Assuming that the instrument meets its specifications, the maximum likely errors when the reading is 05000000 μs is

1. ±251 μs
2. ±260 μs
3. ±261 μs
4. ±250 μs
5.

Answer 1

Correct Answer - Option 4 : ±250 μs

Concept:-

Total errors = Error due to 0.005% accuracy of reading + error due to ±1 in the final digit.

Calculation:-

error due to 0.005% of reading

= 0.005% × 05000000 μs

= 250 μsec.

Error due to ±1 final digit

\(=\pm1\times\frac{1}{10^8}\)

\(\rm [Resolution=\frac{1}{10^n}]\)

= 0.01 μsec

Total error = 250 + 0.01 μsec

= 250.01 μsec.