Wave Interactions

Are You In Need of A Tune Up?Thursday March 29th, 2012

Warm-up: *** Answer in complete sentences on the opposite page if you need room***

1. Identify the relationship between pitch and vibration.

Objective: Students will be able to analyze data in order to explain the relationship among wavelength, frequency, and pitch.

HW: Pd 1,4,5,6 HW #2 Due Tomorrow!!!

Are You In Need of a Tune Up?

INBOXFromDate: Today

I really want the sound manager job at the teen club. The add mentions pitch. Hey, don’t you play the guitar? Do you know anything about pitch?

Yeah, I change the pitch of the sounds when I play music. Do you know how I do that?

Doesn’t it have something to do with the tension on the strings?

Yeah, but I think there’s a lot more to it. If we can figure that out, that job at the teen center will be ours. Let’s figure out what else we need to know.

ClassworkYou have learned that pitch

of a sound is related to the rate of vibrations. Scientists refer to the rate of vibration as frequency. In this investigation, you will collect data about pitch, wavelength, and frequency in order to investigate their relationship.

Investigating Pitch and Frequency2. Record the frequency of each of the tuning

forks in Hertz (Hz).

Tuning Fork 1 =

Tuning Fork 2 =

Tuning Fork 3 =

256 Hz (low C)

320 Hz (E)

512 Hz (high C)

Investigating Pitch and Frequency4. Rank the tuning forks in order from lowest

pitch to highest pitch.

Lowest Pitch =

Medium Pitch =

Highest Pitch =

256 Hz (low C)

320 Hz (E)

512 Hz (high C)

5. Describe the relationship between the frequencies of the tuning forks and the pitch they produce.

The higher the frequency the __________ the pitch.

Investigating Frequency and Wavelength

You have just learned the relationship between frequency and pitch. In this activity, you will utilize investigate how the frequency affects the wavelength of a sound wave produced by tuning forks.

6. Identify the independent and dependent variables in this investigation.

Independent Variable:

Dependent Variable:

Frequency

Wavelength

Problem Question7. Before you begin your investigation you must

have a problem question. Write a problem question for the investigation using the variables you identified.

What is the effect of on wavelength?frequency

8. Write a hypothesis for the investigation:If the frequency

then the will _______________ (increase, decrease, or stay the same)

Because (write your explanation why)

increases

wavelength

C 256 - 5 crests per .02 sec

E 320 - 6 crests per .02 sec

C 512 - 10 crests per .02 sec

Investigating Frequency and Wavelength9. Explain what happens to the number of crests in 0.02 seconds as the frequency increases. Use information from the investigation to support your response.

As the frequency increased, the number of crests increased.

The chart states that the frequency went from 256Hz to 512 Hz (this is an increase). Also, we saw the number of crests at 256Hz was 5, but when the frequency was 512Hz we had 10. This is an increase.

What’s the relationship between frequency and wavelength?

Measure the wavelength!Low C: 256 Hz High C: 512 Hz

Investigating Frequency and Wavelength

10. Identify what happens to the wavelength of the sound waves produced by the tuning fork as frequency increases. Use information from the investigation to support your response.

As the frequency increased, the wavelength decreased.

Exit Ticket1. Compare the pitch, frequency, and

wavelength of the sound waves produced by a 256 Hz and 512 Hz tuning fork.

2. Describe the relationship among frequency, wavelength, and pitch. Use evidence from the investigation to support your response.

ConclusionWrite the conclusion for the investigation. In

your conclusion be sure to include:the problem question being investigated (after

#4)the hypothesis you made (after your problem

question)a statement about the validity of the hypothesis

(was your hypothesis correct)evidence from the investigation to support the

hypothesis (Chart 1)an explanation of the evidence. (Chart 1) State the relationship between frequency and

wavelength.

Sample ConclusionWhat is the effect of __________ on

__________? I hypothesized that if frequency increases, the wavelength will _____________. My hypothesis was _____________ because in Chart 1 it shows that __________________________________________________________. This evidence demonstrates that ______________________________________________________________________________________.