# What is hand stroboscope?

1. Jul 4, 2006

Hello.
What is hand stroboscope ?How is it works ? how can we see anything freez by using the stroboscope ? Please explain.
thankyou

2. Jul 4, 2006

### FredGarvin

If it's what I think it is, it is a handheld light that has a light that turns on and off at a variable frequency. They are used in mechanical environments for determining the speed of an object.

For example, say you have a rotating plate. On the face of the plate is a large dot (not in the center of the plate). As the plate rotates, the dot looks like a circle. Now, if you take a strobescope and start flashing it, you can adjust the frequency at which it flashes until its frequency matches the rotational frequency of the plate. In other words, the light flashes exactly once per revolution of the plate. This scenario will cause the dot to seem to stand still because you are getting a brief look at the wheel at the same instance every single time.

3. Jul 5, 2006

### KingNothing

Great explanation as always fred!

4. Jul 5, 2006

### FredGarvin

Well thank you very much!

5. Jul 5, 2006

### Danger

Aladin, if you want to see one in action, drop by a local service garage and ask to watch them do a timing check on a car. A timing light is a strobe that's triggered by the ignition to show how the tick marks on the harmonic balancer are aligned with a reference line. I'm not sure if newer cars are done the same way rather than by computer, but all of the old ones are.

6. Jul 5, 2006

### Staff: Mentor

I occasionally use one to measure the speed of air handling unit fans.

7. Jul 5, 2006

### Farsight

Last edited by a moderator: Apr 22, 2017
8. Jul 5, 2006

### Danger

That's the poor-man's approach, Farsight. When I was in high-school, my stoner buddy built a box with a disc mounted on a fan motor. It had 2 x 4" diameter holes cut in it, with a red floodlight behind one and a blue one behind the other. The disc also had a 4" hole, and it spun between the lights and the front of the box. His walls were painted in a warped checkerboard black and white, which didn't help. It was absolutely freakish, especially whilst sparking up a gagger with Iron Butterfly playing.

These days, an electronic unit is a lot easier to make or cheaper to buy than a mechanical one.

9. Jul 6, 2006