Measure. Analyze. Learn.
This is the Vernier Light Sensor.
It's a useful sensor, and used in a lot of our different books.
What it does is measure the intensity of light.
It's easy to use. You just aim this part of the sensor
at a light, and it measures the intensity.
It's using the units of lux, and the sensitivity of the switch,
or the device, actually matches, pretty much, the human eye.
And so, it's designed to, kind of, see the light like we see it.
The sensor has a multi-ranged switch here.
And, this allows you to adjust the sensitivity of the device
depending on the light level you're going to be using.
There is a 0 to 600 range,
and that would be fairly dim light conditions.
Maybe you're in a darkened classroom using some small bulbs,
and you want to be able to
measure the intensity of the light of those.
0 to 6000, is a setting that I call, kind of,
normal classroom light level with the lights on.
And then, the 0 to 150,000 level; it's great for outside.
The sun is much, much brighter than the light inside.
And so, having that ability to go outside,
to use that, is what that's for.
So, now we're ready to collect some data,
and what I want to do is plug in the sensor.
It's an analog sensor, so I plug it into the analog port here.
And, I'm going to do an experiment where I measure
the light intensity as the light bulb turns on.
And, to do this,
I need to do my sensor settings a little bit differently.
I need to set it up so that when the bulb comes on,
it causes the device to begin collection all on its own.
And, that's called using a trigger.
And so, we need to set all this up.
If we look at our default setting right now, we've got
the meter here says illumination: '0'.
I've got it set at the most sensitive,
or least sensitive setting actually.
And so, it is expecting a fairly bright light.
But, we'll leave that the same.
And, what I want to do, is I'm going to come up here,
in the upper right corner here [Rate],
and I need to set up my collection parameters.
My default, is 20 samples per second,
but that is not going to be nearly fast enough
for the experiment we're going to do.
And so, I need to set this up to '1000' samples per second.
So, let me do that, and say ok, when it's done.
And, it says 10 seconds.
Well, I really don't need 10 seconds,
because I know from experience that when
I turn the light bulb on, it's going to happen pretty rapidly.
And so, I'm going to change this [Duration]
to maybe just a quarter of a second.
So, I need to do a point-two-five [.25] seconds.
And, I will say 'Done'.
And now, I need to enable the triggering.
And so, this allows the device to wait for something to happen
on the sensor before it collects data.
And so, I going to enable triggering.
And then, I need to set the trigger level.
And what I'm doing is telling it to wait for a certain
light level to be achieved here with the bulb
before it begins collection.
And, I'm going to set this for about 10,000.
I played around with it a little earlier,
and I know that 10,000 lux, which are the units here,
would be fine here.
So I'm going to say 'Done'; and I'll say 'OK'.
And so now, it should be ready for collection.
So, like we do with other sensors, to begin collection,
we press the start/stop button, in the lower left-hand corner.
And, I'm going to press that.
And, it's waiting for the light level to reach the trigger level,
before it actually begins the collection.
I'm going to take the light sensor, hold it up close to the light.
When I turn the bulb on, that causes it to begin collection.
And, we see our graph here.
And so, we are looking at illumination in lux,
and we see that it begins to ramp up here,
but it's also bumpy.
So, we're seeing a little bit more detail than
we might detect with our eyes.
And that, is one of the key reasons to use a device like this.
It allows you to measure things you can't do other ways.
My eyeballs don't detect that the lights flickering at all.
This device does, because we're collecting data
at a much faster rate there.
So, it's a very useful sensor.
It's used across the curriculum in a lot of our different manuals.
And so, it's definitely a good sensor to have.
The sensor booklet talks more about the use of
this particular device.
And so, it has information about the units that are used;
it talks about the spectral sensitivity of the sensor;
so it's a good source of information about the detector.
There's also additional information at our website.