Question

The least count of a stop watch is 0.2 second. The time of 20 oscillations of a pendulum is measured to be 25 seconds. The percentage error in the time period is

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

Answer 1

The correct option is B 0.8 %

Time period of the measurement $T=\frac{t}{n}$

Time of observation $t=25seconds$

Number of oscillation $N=20$

Error in time measurement $\Delta t=0.2s$

Percentage error in time period $\frac{\Delta T}{T}\times 100=\frac{\Delta t}{t}\times 100$

$⟹\frac{\Delta T}{T}\times 100=\frac{0.2}{25}\times 100=0.8$%