Q. Describe Stop watch and its types.

Stop Watch

            A stopwatch is used to measure the time interval between two events. There are two types of stopwatch : Mechanical stopwatch and Digital stopwatch.

 

1. Mechanical / Analogue Stopwatch

            A mechanical stop watch can measure a time interval up to 0.1 second. It has a knob that is used to wind the spring that powers the watch. It can also be used as a start stop and reset button. The watch

starts when the knob is pressed once. When pressed second time, the watch stops While the third press brings the needle back to zero.

 

2. Digital Stopwatch

            A digital stop watch can measure a time interval up to 0.01 second. It starts to indicate the time lapsed as the start/stop button is pressed. As soon as start/stop button is pressed again, it stops and indicates the time interval recorded by it between start and stop of an event. A reset button restores its initial zero setting. Now a days almost the mobile phones have a stopwatch function.

 

Human Reaction Time

            As analogue or digital or watch is operated by human manually i.e., they have to be started or stopped by hand. This causes a random error in measurement of time i.e called human reaction time.