Our Senses – Investigation 1 CAP
Our Senses – Investigation 1: CAP
In this CAP we will follow up on a part of the lab for Investigation 1. We will discuss the tuning fork further and accentuate to students the connection between vibration and sound. After a few slides aimed at getting students to understand that the tuning fork vibrates when struck on the rubber stopper and that our ears perceive the vibration as sound, we will perform two quick and simple experiments.
We want to establish, by the end of this CAP, that vibrations make sound and sounds make vibrations.
This slide is included simply to remind students that they used a tuning fork in lab to produce sound. It asks the important question, “Why do you think you heard the tuning fork when it was tapped on the rubber stopper?“. The answer, of course, is that tapping the tuning fork caused it to vibrate.
This slide graphically shows that tapping the tuning fork causes it to vibrate. It further goes on to say that the vibrations from the tuning fork travel through the air and enter our ears.
This slide ties the perception of vibrations to hearing. When vibrating air enters our ear, it causes our ear drums to also vibrate, just as the skin of a drum vibrates when it is hit. Through a series of rather more complicated steps, the vibrating ear drum is interpreted by our brain as sound.
This slide describes the first of two experiments that students may do at their desks or the teacher may choose to do as a demonstration. If the latter, be sure that each student is able to come close enough to both hear the sound produced and see the vibration of the ruler or meter stick.
Suggestion: Try to play a simple song (like Mary Had a Little Lamb) by changing the length of the meter stick extending over the edge of the table. You might even try writing down the distance of each length in centimeters and have someone else try to play the song using the “notes” (lengths) you wrote down!
Below is a fun video:
This final slide describes a very simple experiment that each student can do at his or her desk. When holding one’s hand on one’s throat in silence, no vibration is felt because no sound is being produced. Upon either humming of simply talking, students will feel the vibrations coming from their throats as well as hear the sound produced.
This is a very direct demonstration of the essential link between vibration and sound. The experiment can be extended by noticing that the louder the sound is produced (by humming or talking louder), the stronger the vibration will be.