Adjustable Hand Stroboscope, how to use?

[FortranMan]

What kind of lab activity would you use an Adjustable Hand Stroboscope for?
https://prolabscientific.com/Educat...Stroboscopes/Hand-Stroboscope-Adjustable.html
Would it purely be a qualitative activity? I can't imagine you can do anything really quantitative with it unless you attached it to a motor. Maybe you would have students watch each other walk or watch a moving car with a ruler or measuring tape in the back, then they record the position they saw their partner at. I wish it had more functionality as you can adjust how many frames per rotation the student could see.

 

[berkeman]

What other devices do you have in your lab that you can use for this experiment? Do you have an oscilloscope? And/or a frequency counter?

I can't tell how they intend the disks to be used. Do you attach them to a motor and spin them and look through the slots, or do you try to shine a light through the slots as it spins and watch the illumination on a moving/oscillating object?

With a normal strobe light, you illuminate some oscillating object at different frequencies and find the fundamental oscillation frequency. Then you can also demonstrate aliasing from undersampling, and other sampling effects. It's best to have a calibrated strobe light or use and oscilloscope/frequency counter with an LED or other light pickup device.

 

[jim mcnamara]

It can be used to "freeze" motion - see https://spark.iop.org/hand-stroboscope

 

[berkeman]

see https://spark.iop.org/hand-stroboscope

I like that they include a safety warning; I didn't even think of that!

Safety

Photo-induced epilepsy only accounts for 1% of epileptic attacks, but it is the frequency of flashing rather than the light intensity which causes it. For this reason, a safety note about photo-induced epilepsy is given whenever any type of stroboscope is used.

 

[256bits]

One holds the centre handle with one hand and puts a finger of the other hand through the finger hole just off centre to spin it around.

Rotation rate x number of open slots gives the strobe frequency.
If you rotate 5 revs per second, a strobe disk of 12 slots would give out a 60 Hz frequency, so you would have to look for low frequency oscillations to freeze frame. Maybe a vibrating bar in a vice.

You could make one of these.

https://en.wikipedia.org/wiki/Phenakistiscope#Scientific_use
The beginnings of the motion picture industry

 

[FortranMan]

It can be used to "freeze" motion - see https://spark.iop.org/hand-stroboscope

Thank you. Sounds like I could have them watch a spring oscillator and have them measure their disk rotation speed for different slot numbers. Didn't know the hole was so they could keep spinning the disk at constant speed, though it still may be tricky for them.