Click HERE to download from Google Play Store a wonderful Science App "Strobe".
This Android App turn your smart phone into a full pledged stroboscopic light source.
A strobe light can be used in the following ways:
This Android App turn your smart phone into a full pledged stroboscopic light source.
Strobe App Page
1. You can stop your fan without switching it off and without harming yourself. Yes that sounds crazy but that you can do. All you need is a dark room with a fan revolving in it. Just adjust the frequency of the strobe as accurately as possible to stop the fan. Of course the fan is not stopped, it is still revolving as you can feel from the air flow. But when the blades of your fan rotate by such an angle that one blade replaces the succeeding blade in its' position when the next flash of light comes in, the fan seems to stand still. If you have '$N$' blades equally angled apart(They must be equally angled apart. Why ? Think friend Think), the condition is that,
\[\frac{m}{f_{flash}}=\frac{60}{N\times RPM}\]
Whereas $m$ is an integer ( $m=1,2,3...$ ) and $RPM$ is the Revolutions Per Minute of the fan.
If we rearrange the above equation we get,
\[RPM =\frac{60 \times {f_{flash}}}{m \times N}\]
The rotational speed of the fan in $RPM$!
\[\frac{m}{f_{flash}}=\frac{60}{N\times RPM}\]
Whereas $m$ is an integer ( $m=1,2,3...$ ) and $RPM$ is the Revolutions Per Minute of the fan.
If we rearrange the above equation we get,
\[RPM =\frac{60 \times {f_{flash}}}{m \times N}\]
The rotational speed of the fan in $RPM$!