Question

Which of the following time measuring devices is most precise?
(a) A wall clock.
(b) A stop watch.
(c) A digital watch.
(d) An atomic clock.
Give reason for your answer.

Answer 1

(d) atomic clock     
because it is on corrected of 0.002 seconds in one lakh year

Answer 2

(d) An atomic clock is the most precise measuring device.