Question

Q.13 A stopwatch has a circular dial divided into 120 divisions . Time interval of 10 oscillations of a simple pendulum is measured as 25 seconds by using the watch . Maximum percentage error in the time period is (1) 1 % (2) 2 % (3) 3 % (4) 4 %

Answer 1

Dear Student ,

If the hand of the stopwatch makes 1 revolution in a minute, and each revolution is divided into 120 divisions then the smallest division corresponds to 60/120 = 0.5 sec.​

No. of oscillations = 10

Time taken for 10 oscillations = 25 s

Time period = 25/10 = 2.5 s

Now least count of the watch = 0.5 s

In the measurement of time period the of 2.5, the measuring watch can measure upto 0.5 s.

Thus error = 0.05s

Percent error = (0.5/2.5) × 100 = 4%
​Regards