Question

What is the least count of digital stopwatch?
${\text{A}}{\text{.}}$ 0.2 s
${\text{B}}{\text{.}}$ 0.1 s
${\text{C}}{\text{.}}$ 0.3 s
${\text{D}}{\text{.}}$ 0.01 s

Answer 1

Hint- Here, we will proceed by defining stopwatches. Then, we will specify the various functions performed by stopwatches. Then, we will define the term least count for any measuring instrument along with its value for digital stopwatch.

Complete step-by-step solution -
Stopwatches are watches that measure the time of the events. Instead of telling one the time of day, the stopwatch tells the person how long it took to perform a certain function. Some stopwatches can time multiple events. Some stopwatches can time parts of the event along with the total time of the event.
The stopwatch contains buttons to perform certain functions, such as starting, stopping and split timing. Various stopwatches can also have other functions such as an alarm or calendar function.
Digital stopwatches are more accurate. Mechanical stopwatches are powered by a mainspring, which must be periodically wound up by turning the knurled knob at the top of the watch. It is designed to be manually started. Any measurement made by the instrument can be considered repeatable to no less than the resolution of the least count.
Least count of a measuring instrument is the smallest and accurate value in the measured quantity that can be resolved on the instrument's scale.
In the case of a digital stopwatch, the minimum value of the time which can be measured is 0.01 seconds.
Hence, option D is correct.

Note- The least count is related to the precision of an instrument. An instrument that can measure smaller changes in a value relative to another instrument, has a smaller least count value and is more precise. The least count of an instrument is inversely proportional to the precision of the instrument.