Question

The least count of a stop watch is $0.2\, s$. The time of $20$ oscillations of a pendulum is measured to be $25\, s$. The percentage error in the time period is

• A. $16\%$
• B. $0.8\%$
• C. $1.8\%$
• D. $8\%$

Answer 1

Answer: (B)

$0.8\%$

Answer 2

$\Delta t=0.2\,s$ $t=25\,s$ $T=\frac{t}{N} \,\Rightarrow \, \frac{\Delta T}{T}=\frac{\Delta t}{t}=\frac{0.2}{25}$ $=0.8\%$