# High School Physics : Properties of Waves

## Example Questions

### Example Question #32 : Waves

After exercising, Jane takes her pulse. She realizes that her heart is beating rapidly, approximately four beats every second. What is the period of her elevated heart rate?      Explanation:

When you see a relationship like "times every second" or "once per hour," these are hints you are looking at a frequency. Frequency is, effectively, how often something happens. If it happens four times per second, then we know how often it happens. The units "per second" are equivalent to Hertz.

The relationship between frequency and period is .

Since our given frequency was four beats per second, or , we can solve for the period. This means that her heart beats once every seconds.

### Example Question #2 : Properties Of Waves

A wave oscillates with a speed of and has a wavelength of . What is the frequency of the wave?      Explanation:

The equation for velocity in terms of wavelength and frequency is .

We are given the velocity and the wavelength. Using these values, we can solve for the frequency.    ### Example Question #3 : Properties Of Waves

A wave with a constant velocity doubles its frequency. What happens to its wavelength?

The wavelengths will be the same.

The new wavelength will also double.

The new wavelength will be 12  the old wavelength.

There is insufficient information to solve.

The new wavelength will be 12  the old wavelength.

Explanation:

The relationship between velocity, frequency, and wavelength is: In this case we're given a scenario where and . The velocities equal each other because the problem states it has a constant velocity. Therefore we can set these equations equal to each other: Notice that the f's cancel out: Divide both sides by two: ### Example Question #41 : Waves

Two notes are played simultaneously. One of them has a period of and the other has a period of . Which one has a longer wavelength?

We need to know the frequency in order to solve

We need to know the period in order to solve They have the same wavelength  Explanation:

The relationship between frequency and wavelength determines the velocity: The frequency is the inverse of the period. We can substitute this into the equation above. In the question, both of the notes are played at the same time in the same location, so they both should have the same velocity. We can set the equation for each tone equal to each other. We are told that . Substitute into our equation. We can cancel the period from each side of the equation, leaving the relationship between the two wavelengths. The wavelength of the first wave is equal to half the wavelength of the second. This means that the wavelength for the tone with a longer period will have a longer wavelength as well.

### Example Question #5 : Properties Of Waves What is the wavelength of the wave above?     Explanation:

The wavelength of a wave is defined as the distance from a point on the wave to the same point on the wave (crest to crest or trough to trough).  The distance between peaks is .

### Example Question #6 : Properties Of Waves What is the amplitude of the wave above?     Explanation:

The amplitude of wave is defined as the distance the wave displaces from the equilibrium point.  In this case, the wave displaces from the axis (the equilibrium point).

### Example Question #7 : Properties Of Waves

A wave has a frequency of . What is its period?      Explanation:

The relationship between frequency and period is .

Plug in our given value:   ### All High School Physics Resources 