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

Options

A. `8%`
B. `0.8%`
C. `1.8%`
D. `2%`

Answer

B

Explanation

Time period of oscillations can be written as follows ,
`T=(25)/(20)=1.25s`
Error in the measurement of time of 20 oscillations is 0.2s, hence corresponding error in the measurement of time period can be written as follows :
`triangleT= (0.2)/(20)=0.01s`
Percentage error in the measurement of time period can be written as follows :
`(triangleT)/(T)xx100=(0.01)/(1.25)xx100=0.8%`