# Phyiscs- Beats and frequency problem

• CivilSigma
In summary: Now, if we take a closer look at question 4 we see that it asks which of the two frequencies is correct if the initial frequency is 300 hz. Now, since the frequency of the unknown fork can only be either 297 or 303 hz, if we add the plasticine to the known fork with the correct frequency (303 hz), the beat note will stay the same, since it is still being generated by the unknown fork. However, if we add the plasticine to the unknown fork with the incorrect frequency (297 hz), then the beat note will change since it will now be generated by the known fork instead of the unknown one.
CivilSigma

## Homework Statement

Plasticine (which lowers the pitch) is added to one tine of the tuning forks of unknown frequency referred to in question #4 (initial frequency = 300 Hz possible frequencies 303 Hz or 297 Hz). The number of beats decreases to one(per second). What was the frequency of the unknown fork?

## Homework Equations

fb=f2-f1 or f1-f2

## The Attempt at a Solution

Well, i know how to calculate the beat difference, but I do not under stand which of the 303Hz or the 297Hz referred to question #4 are the correct initial frequencies before adding the Plasticine! Can some one explain that to me please!

I don't think I understand the question. Could you include the problem statement for #4?

sakonpure6 said:
Well, i know how to calculate the beat difference, but I do not under stand which of the 303Hz or the 297Hz referred to question #4 are the correct initial frequencies before adding the Plasticine! Can some one explain that to me please!
Hi sakonpure6. You're providing the answer, so I'll try to figure out the question ...

It sounds as though you have 2 tuning forks with a certain beat frequency. You then add plasticine to one of the tines, the effect being to lower the resonant frequency of that fork. If in doing so the beat frequency reduces to 1Hz, what was that fork's resonant frequency without the plasticine?

I think you still need some detail from the question #4 that you allude to, though I'm left to guess.

Last edited by a moderator:
Since I can't see the edit button, here is question 4 and I really appreciate this guys!

Two tuning forks are sounded together, producing three beats per second. if the first fork has a frequency of 300 Hz , what are the possible frequencies for the other fork?

The answers are: 297Hz and 303Hz

sakonpure6 said:
Two tuning forks are sounded together, producing three beats per second. if the first fork has a frequency of 300 Hz , what are the possible frequencies for the other fork?

The answers are: 297Hz and 303Hz
In reality, that second fork must have a frequency of 297Hz or 303Hz, it can't have both fundamentals simultaneously. On the data given for this part of the question, we can't determine which of those two frequencies it does have.

So the next part resolves to: what must have been done to bring about a beat frequency of just 1Hz?

I really don't get it! >.< this is the only concept I am having a hard time understanding even when the teacher tries to explain it! May you please show me how you would do it! Thank you for your time.

Maybe this will help: You have determined that the unknown tuning fork has a frequency of either 297 or 303 based on the 3 Hz beat note. Now the problem is how do you determine which of these two frequencies is correct. In your first statement, you say that if you add Plasticine to the fork, the frequency will lower. So, if you add the plasticine to the fork what will happen to the beat note depending on whether the unknown frequency is 297 or 303 hz.

## 1. What is the concept of beats in physics?

In physics, beats refer to the interference pattern that occurs when two sound waves of slightly different frequencies are played together. These waves interfere with each other, resulting in a periodic increase and decrease in amplitude, which is perceived as a beat.

## 2. How do you calculate the beat frequency?

The beat frequency can be calculated by taking the absolute value of the difference between the two frequencies of the sound waves. This can be expressed as fbeat = |f1-f2|, where f1 and f2 are the frequencies of the two sound waves.

## 3. What is the relationship between beat frequency and frequency of the individual waves?

The beat frequency is equal to the difference between the frequencies of the two waves. This means that as the frequency of one wave increases, the beat frequency also increases. However, if the frequency of one wave is much higher than the other, the beat frequency may not be noticeable.

## 4. How does the amplitude affect beat frequency?

The amplitude of the sound waves does not affect the beat frequency. It only affects the loudness or intensity of the sound. The beat frequency is solely determined by the difference in frequencies between the two waves.

## 5. Can beat frequency be observed with electromagnetic waves?

Yes, beat frequency can also be observed with electromagnetic waves, such as light or radio waves. In this case, the interference pattern is not audible, but can be seen in the form of bright and dark fringes. This phenomenon is commonly used in experiments to measure the frequency of light.

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