A chopping wheel and a camera are used
to show the Strobe Effect.
Watch Video:
Teachable Topics
- Optics
- Photography
- Frequency
Theory:
In this demo we can see the strobe effect. This happens when an object in continuous motion is represented by a series of small sections, or pictures in the case of the video camera. The video camera takes pictures of the wheel at (usually) 30 frames per second, and strings these together to make the video.
The strobe effect becomes apparent when the frequency of the wheel approaches the frequency (or n x freq) of the camera and begins to look like it is slowing down. This example of the strobe effect is apparent in films and television, and is also known as the "wagon wheel effect."
Apparatus:
- Digital video camera
- Chopper wheel
- Chopper controller
- Light Source
Procedure:
- Set a rotating object in motion as an angular frequency close to an integer multiple of the fps (frames per second) of the camera
- Start the camera. Keep the relative motion of the camera and the object constant.
- Adjust the frequency while watching the video feed to see strobing.
SAFETY WARNINGS:
- Don't stare into the light
- Keep objects and fingers away from chopper wheel while it is spinning.
