Question

The least count of a stop watch is $\frac{1}{5}s$. The time of 20 oscillations of a pendulum is measured to be $25s$. What is the maximum percentage error in this measurement ?

• A. $8\%$
• B. $1\%$
• C. $0.8\%$
• D. $16\%$

Answer 1

Answer: (C)

$0.8\%$

Given,

Least count, $\frac{1}{5}=0.2\sec$

Total time measurement: $25s\pm 0.2s$

For $20$ oscillation

Error in one oscillation: $\frac{25s\pm 0.2s}{20}=1.25s\pm 0.01s$

Hence Percentage error: $\frac{0.01}{1.25}\times 100=0.8$%