The Caliper
A Publication for Users of Vernier Products

Vernier Photogate

Lots of new functions-at the same low price
We’ve updated the Vernier Photogate with three new features:
1. The gate is now auto-ID, so that when used with Logger Pro 3 and LabPro, the gate is automatically identified and the software is configured for photogate data collection.
2. You can now connect up to four photogates on a single LabPro or CBL 2 digital input using the new daisy-chain feature.
3. Best of all, the new Vernier Photogate includes a laser switch port. The laser switch option lets you create a very wide photogate using an ordinary laser pointer as a light source. You simply direct the laser beam into the laser port on the side of the gate. We’ve tested the gate with the laser 20 meters away, so you could literally drive a truck through this photogate. Use the laser gate to measure the speed of a runner, a car, or a full-size roller coaster.

What’s Your Hang Time?

The new Vernier Photogate allows you to create human-scale timing gates. For example, it is a simple matter to create a hang-time meter. How long can a good jumper remain in the air? Let’s find out.

Set a laser pointer on the floor so that the beam is just barely above floor level, aimed for a new Vernier Photogate about a meter away.
(Hint: You can use a standard office binder clip to keep the power switch depressed on a pen laser. That also keeps it from rolling away!) Next, use the new flexible timing modes in Logger Pro 3 to measure from the time the gate becomes unblocked to when it is blocked. That’s an unusual timing choice, but it’s perfect for this experiment. Open the file jump.xmbl to see the set up.

Start data collection, then step into the gate so your feet are blocking the laser beam. Jump as high as you can, landing again to block the beam.

Logger Pro 3 will report the result with photogate precision. From the jump time, we can even have Logger Pro 3 find the maximum height your center of mass rose. Have students who are basketball players and ballet dancers compare their results.