Technoteacher - Day 2

What’s That Noise?

Some robot systems use sound sensors to pinpoint moving objects. They’re able to locate the object by interpreting the sounds it makes.

Do the following experiment:

Ask a student to sit in a chair, then ask another student to move around behind him or her while shaking a jar of beans. The seated student has to guess where the sound is coming from. There’s a reason why s/he isn’t always right. When the sound is at an equal distance from each ear, it’s hard to locate.

Ticking Sensor

The ear is a sound sensor. Try the following experiment with students to help them understand how a sensor works.

Procedure

1. Hold a watch next to a student’s ear and move it away until s/he can no longer hear it ticking.
2. Then hold one end of a cardboard tube up to the student’s ear and put the other end on the watch. The sound is amplified.

Explanation: soundwaves need energy to travel. As soundwaves begin to disperse, they lose energy; but when the waves are trapped in a sensor tube, the energy doesn’t dissipate as quickly and the sound is amplified. This is the principle behind a sensor.

Paper Clip Sensor

Electricity is the form of energy that powers most sensors. To illustrate this mechanism, build an electromagnet with students.

You’ll need:

	a 4.5-volt battery
	electrical wire
	sticky tape
	a screwdriver
	a switch (made of a paper clip attached to a piece of cardboard with a brass clip)

Procedure

1. Strip the ends of the wire. Tape one end of the wire to the screwdriver handle.
2. Wrap the wire firmly around the screwdriver, taping the last loop of wire to the screwdriver.
3. Touch the exposed ends of the wire to the battery.

Show how the electromagnet works by having it pick up paper clips spread out on a flat surface.

Observation: the more times the wire is wrapped around the screwdriver, the stronger the magnet. Lead a discussion on sensors. Suggest that students research the topic.