AP Physics 1 : Wavelength and Amplitude
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Example Questions
Example Question #1 : Wavelength And Amplitude
A severe storm has moved into your area and the weather sirens have begun to go off. The frequency of the siren ranges between 200 hz and 2,000 hz. What is the range of wavelength of the emitted sound waves?
We can use the following equation to solve this problem:
where
v = velocity of sound
f = frequency
Rearranging for wavelength, we get:
Plugging in our values, we get:
You do not need to have this equation memorized in order to solve this problem. A very useful skill in physics is being able to solve problems based solely off your units.
We need to have an answer with the units of meters. We are given units of m/s and 1/s. How can we go from these to meters? Simply divide the value with the units of m/s by the value with the units of 1/s. This gives you an answer with the units of meters. Once written out, this is the final equation written above. No need to spend extra time memorizing the equation!
Example Question #1 : Wavelength And Amplitude
What is the wavelength of a radio station that broadcasts at 92.9MHz?
We need to know the speed of light, which is:
We can use this to calculate the wavelength of any electromagnetic wave if we know the frequency, using the equation:
If you're unsure of how to come about this equation, you should be able to derive it by looking at your units. Use our given values to solve for the wavelength:
Example Question #32 : Waves
A wave with a speed of 
Since the wave has a frequency of 30Hz, we know it completes 30 cycles every second. As its velocity is 
Example Question #33 : Waves
Given the speed of a wave as 
Speed is frequency times wavelength. So the frequency must be speed divided by wavelength. In this case:
This makes sense as in one second, the wave will have travelled 15m. Each meter is 5 cycles, so over the distance the wave has travelled in one second, it has completed 
Example Question #34 : Waves
An equation of a wave is given by the following formula:
Here, 
A trigonometric equation given by the following formula
Here, 
In our case:
Example Question #35 : Waves
The music we listen to on the radio is transmitted in the form of radio waves. You might have seen that a radio station on FM is broadcasted in 
What is the wavelength of a radio wave if it's being transmitted on a frequency of 
Radio waves travel at the speed of light 
In our case,
Therefore,
Example Question #36 : Waves
An original signal's frequency is halved by a resistor, and no other part of the wave is effected. Determine the change in the amplitude of the signal.
The amplitude is halved
The amplitude is unchanged
The amplitude is doubled
The amplitude is quadrupled
The amplitude is unchanged
Amplitude refers to the strength of a wave and has no relation to its frequency. Frequency would only affect the period and phase, but not the amplitude.
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