Question

Which of the following time measuring devices is most precise?
A.) A wall clock
B.) An atomic clock
C.) A digital watch
D.) Stop watch

Answer 1

Hint: A measuring device is considered less or more precise in terms of their least count. A device with the lowest least count is always taken as the best measuring device. So, the answer can be found out by comparing the least count of the given tie measuring devices.

Complete step by step solution:
An instrument is considered more precise, if its least count is less compared to other measuring devices. The means, the device that can measure the smallest change in any unit is the most precise one.

here, we have been given four time measuring devices, whose least counts are as follows

Wall clock – 1 sec
Atomic clock – $10^{-13}$ sec
Digital watch – 0.001 sec
Stopwatch – 0.1sec

Hence, option b is the correct answer.

Additional information:
Atomic clock is the most precise time standard known, and it is used as primary standards for the distribution of time internationally. It is also used to control the broadcast timings of televisions globally and in Global Processing Systems. This clock works on the principle of atomic physics and measures the electron signal emitted by an electron while they change their energy levels in an atom.

Note: The least count and precision of an instrument are inversely proportional to each other. The smaller the least count value, the more precise the instrument will be. So, instruments with smaller least counts are always considered for measurements.