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Resonance is a phenomenon that is associated with musical instruments - Leaving Cert Physics - Question 7 - 2018
Question 7
Resonance is a phenomenon that is associated with musical instruments. What is resonance? Describe an experiment to demonstrate resonance. A stretched string of a v... show full transcript
Worked Solution & Example Answer:Resonance is a phenomenon that is associated with musical instruments - Leaving Cert Physics - Question 7 - 2018
Step 1
What is resonance?
Answer
Resonance is the transfer of energy between two bodies vibrating at the same natural frequency. This phenomenon can be demonstrated with a simple experiment using tuning forks.
Experiment to Demonstrate Resonance
- Materials Needed: Two tuning forks of the same frequency and a wooden board.
- Procedure: Strike one tuning fork and place it next to the wooden board. This will vibrate the board. Then strike the second tuning fork; it will vibrate without direct contact due to the resonance effect.
Explanation
The energy from the vibrating tuning fork is transferred to the board and then to the second tuning fork, causing it to vibrate, demonstrating resonance.
Step 2
Calculate the tension in the string
Answer
To calculate the tension in the string, we use the formula:
egin{align*} ext{mass per unit length, } \mu &= \frac{m}{L} = \frac{0.126 \times 10^{-3} \text{ kg}}{0.328 \text{ m}} \approx 3.84 \times 10^{-4} \text{ kg/m} \\ f &= \frac{1}{2L} \sqrt{\frac{T}{\mu}} \\ 660 &= \frac{1}{2(0.328)} \sqrt{\frac{T}{3.84 \times 10^{-4}}} \\ \Rightarrow T \approx 72 \text{ N} \end{align*}Step 3
Step 4
Draw a labelled diagram to represent the fundamental frequency of a stationary wave in a pipe that is closed at one end
Answer
The labelled diagram should depict a closed-end pipe with a node at the closed end and an antinode at the open end. The fundamental frequency will appear as a single loop within the pipe.
Step 5
Step 6
Describe the effect of doubling the distance from the source to an observer on the sound intensity measured
Answer
When the distance from the sound source to the observer is doubled, the sound intensity measured decreases by a factor of four. This is because sound intensity follows the inverse square law:
(iii) The sound intensity measured
- The sound intensity becomes smaller.
(iv) The sound intensity level measured
- The sound intensity level measured decreases by approximately 6 decibels.