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 second. The percentage error
in the measurement of time will be
(a) 8% (b) 1.8%
(c) 0.8% (d) 0.1%

Answer 1

Answer:

Number of oscillations n=20

Time taken =25 s

∴ Time period of oscillation T=

20

25

=1.25 s

Given :

Error in time for 20 oscillations, ΔT=0.2 s

Hence error in time for 1 oscilations, ΔT

′

=

n

0.2

= s

∴ Percentage error =

T

ΔT

×100=

20×1.25

0.2

×100=0.8 %