Question

The least count of a stop watch is $0.2\text{s}$. The time of 20 oscillations of a pendulum is measured to be $25\text{s}$. The percentage error in the measurement of time will be:
(correct answer + 1, wrong answer - 0.25)

• A. $16\%$
• B. $1.8\%$
• C. $0.8\%$
• D. $0.1\%$

Answer 1

The correct option is C $0.8\%$

The least count of stopwatch is $=0.2\text{s}$
Time period of 20 oscillation = $25.0\pm 0.2\text{s}$
Percentage error in measurement = $\frac{0.2}{25.0}\times 100=0.8\%$