Frequency and wavelength are properties associated with waves - Leaving Cert Physics - Question 8 - 2017
Question 8
Frequency and wavelength are properties associated with waves.
(i) What is meant by the frequency of a wave?
(ii) State the relationship between the frequency of ... show full transcript
Worked Solution & Example Answer:Frequency and wavelength are properties associated with waves - Leaving Cert Physics - Question 8 - 2017
Step 1
What is meant by the frequency of a wave?
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Answer
The frequency of a wave refers to the number of wave cycles that pass a given point per unit time, typically expressed in Hertz (Hz).
Step 2
State the relationship between the frequency of a wave and its wavelength.
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The relationship between frequency (f) and wavelength (λ) is given by the formula:
v=fimesextλ
where v is the speed of the wave in a given medium.
Step 3
What name is given to this effect?
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This effect is known as the Doppler effect.
Step 4
Explain, with the aid of a labelled diagram, how this phenomenon occurs.
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The Doppler effect occurs when there is a relative motion between a wave source and an observer. As the ambulance approaches, the sound waves are compressed, leading to a higher frequency (pitch). Conversely, as it moves away, the sound waves are stretched out, resulting in a lower frequency. The labelled diagram should depict the wave front compression as the source moves toward the observer and the stretching of waves as it moves away.
Step 5
Name one practical application of this phenomenon.
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One practical application of the Doppler effect is in radar technology, which is used for measuring the speed of moving objects such as vehicles, or in medical imaging to study blood flow.
Step 6
What does this indicate about the difference between sound waves and light waves?
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The observation that light from an electrical storm is seen before the sound is heard indicates that sound waves travel slower than light waves. This demonstrates the significant difference in propagation speeds between the two types of waves.
Step 7
State one other difference between sound waves and light waves.
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Sound waves are longitudinal and require a medium to travel, while light waves are transverse and can propagate through a vacuum.
Step 8
Calculate the difference in time the runner would receive if the stopwatch was started at exactly the same time as the starting gun was fired.
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Answer
The time taken for sound to travel 100 m can be calculated using the speed of sound:
If the runner’s stopwatch started when hearing the gun, there would be a delay of approximately 0.303 seconds compared to starting the stopwatch at the same time as the gun fired.
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