Question

During a race, if an analog stop watch with $1200$ circular scale divisions is used, then find what will be the minimum human reaction time error (considering error can't be zero).

• A. $\pm 1s$
• B. $\pm 0.5s$
• C. $\pm 0.1s$
• D. $\pm 0.05s$

Answer 1

Answer: (D)

$\pm 0.05s$

Time period of stop watch is $60$ seconds.
Number of divisions $N=1200$
Minimum human reaction time error (or least count) $LC=\pm \frac{60}{1200}=\pm 0.05s$