Physics- waves

[LMartinez]

i know that the velocity of a wave directly corresponds to the medium. does the same apply to the wavelength? does the wavelength change when a wave moves from one medium to another?

I am confused because my MCAT book says that frequency and wavelength do not affect velocity, that an alteration in wavelength does no affect the wave speed... but it also says that velocity and wavelength are directly proportional. how is this possible?

---

Members don't see this ad.

 

[Zenabi90]

i know that the velocity of a wave directly corresponds to the medium. does the same apply to the wavelength? does the wavelength change when a wave moves from one medium to another?

Yes, a change in medium causes a change in speed, which corresponds to a proportional change in wavelength. V = f * w
The frequency depends on the source, not the medium.

I am confused because my MCAT book says that frequency and wavelength do not affect velocity, that an alteration in wavelength does no affect the wave speed... but it also says that velocity and wavelength are directly proportional. how is this possible?

Are you oversimplifying or misinterpreting your MCAT book? For example, in terms of light, all colors of light travel at the same speed, but each color varies in wavelength and proportionally, varies in frequency.

To combine the two concepts, this is how refraction causes a dispersion of white light to create a rainbow.

 

[BerkReviewTeach]

The key thing to keep in kind is whether the medium remains constant. The source of a wave sets its frequency, so that remains constant, even when changing medium. The speed and wavelength must have correlated values in a given medium: f =v/lambda. However, if you change medium (such as sound going from air to water), the wavelength must change in the same way and with same magnitude as the speed, which keeps the frequency constant.

You definitely studied this with refraction of light, which appears to bend as it passes from one medium to another, if the incident ray is not perpendicular to the interface. When visible light passes from air into water, for instance, it slows and the wavelength shortens. As it happens, blue light slows and shortens more than red light, leading to dispersion.

For questions on waves, you need to ask yourself a few questions before tackling the question. (1) Did the medium change? and (2) is the source or receiver in motion? Many of the questions you will see on waves will be based on one of those two possibilities.