Wavelength and Frequency: Videos & Practice Problems

Light energy travels as electromagnetic radiation, which can be viewed as either particles or waves. The wavelength, denoted by the Greek letter lambda (λ), measures the distance between successive crests or troughs of a wave in meters. Frequency, symbolized by the Greek letter nu (ν), is the count of waves passing a point per second, expressed in hertz (Hz) or seconds inverse (s⁻¹). Amplitude is the wave's height from the origin to the crest or trough. These three properties are fundamental to understanding electromagnetic waves. Additionally, frequency and wavelength share an inverse relationship at a fixed speed; as frequency increases, wavelength decreases, and vice versa. This concept is crucial for comprehending the behavior of light as electromagnetic radiation.

Electromagnetic Waves

Now light energy can travel through space as electromagnetic radiation in the form of either particles or waves. Now this is a highly debated topic within the scientific community. See some see light as individual particles or as others see light as a big wave filled with clusters of these particular particles.

Now wavelength itself. We use the Greek symbol λ and it's just a distance from 1 Crest or top of a wave, or the trunk the bottom of a wave to the next wave. Here it's expressing units of meters and with wavelength we have frequency. Frequency uses the Greek letter ν which looks like AV. It's a number of ways you have per second. Here it's expressed in units of either seconds, inverse, or Hertz. So they're the same thing.

Associated with wavelength and frequency we have amplitude, which is just the height of a wave measured from the origin to its Crest or from the origin to its through. Now here, if we take a look at this wave, we're going to say that our origin here is 0 kind of cuts through the wave right in the middle. We're going to say the distance from 1 Crest to another Crest or one through to another through. That represents our wavelength.

We're going to say the height from the origin up to the Crest or the origin to the through represents our amplitudes. So amplitude here and amplitude here. And then finally how many ways you get per second represents our frequency. OK, so these are the three ideas attached to any electromagnetic wave that we observe. Now that we know these three topic, let's move on to the next video.

Wavelength and Frequency Example

Here in this example question, it says based on the images given below, which electromagnetic wave has the highest frequency. All right, so these waves look a bit different from one another. But remember that our frequency is how many wings we can get within a given amount of time. So here we can say in terms of a second.

Now if we were to say that all these lines represent the same amount of time that is elapsed, let's just say that these, even though they're not drawn to scale, let's just say that they're all the same amount of time that's elapsed. The one that would give us the most amount of overall waves would represent the one with the greatest frequency.

If we look at each of the options 1-2 and three, we can see that option three is the best answer. It is the one that depicts most amount of waves within the set amount of time. Remember, the more waves you have per given amount of time represents a higher frequency. So option three would give us the highest frequency shown.

Frequency-Wavelength Relationship

So when it comes to frequency and wavelength, just realize that at a fixed speed, the frequency of a light wave is inversely proportional to the wavelength. That basically means that they're opposites of one another.

So that means that the higher our frequency becomes, then the lower our wavelength, and the lower our frequency becomes, the higher our wavelengths. So just for keep in mind this inverse relationship between frequency and wavelength when it comes to any electromagnetic wave at a fixed speed.

Which energy wave would have the highest frequency from the wavelengths provided?

• A. Wave A (453 nm)
• B. Wave B (707 nm)
• C. Wave C (325 nm)
• D. Wave D (910 nm)

Answer: (C)

Here’s what students ask on this topic:

What is wavelength?

Wavelength is a fundamental concept in physics, particularly in the study of waves and optics. It's defined as the distance between two consecutive points that are in phase on a wave. In simpler terms, if you imagine a wave as a series of peaks and troughs, the wavelength is the distance from one peak to the next, or from one trough to the next. It's typically measured in meters, but can also be expressed in other units of length depending on the scale of the wave.

Wavelength is inversely related to frequency, which is the number of waves that pass a given point in one second. This relationship is described by the equation:

$v=\lambda \times f$

In the context of light waves, wavelength determines the color of the light; for example, red light has a longer wavelength than blue light. In sound waves, the wavelength affects the pitch of the sound: a longer wavelength corresponds to a lower pitch, and a shorter wavelength corresponds to a higher pitch.

What is frequency?

Frequency refers to the number of times a particular event occurs within a specific period. In physics, it's most commonly associated with waves, including sound waves, light waves, and electromagnetic waves. The frequency of a wave is the number of cycles (such as peaks or oscillations) that pass a fixed point in space per unit of time. It is measured in hertz (Hz), where one hertz equals one cycle per second. For example, if you're looking at a sound wave and you count that 440 cycles occur in one second, that sound wave has a frequency of 440 Hz, which corresponds to the musical note "A" above middle C on a piano. Frequency is an important concept because it determines the pitch of sounds, the color of light, and is a key characteristic in the transmission of signals in electronics and communications.

What is the relationship between wavelength and frequency?

The relationship between wavelength and frequency is an inverse one, governed by the speed of light for electromagnetic waves, or the speed of sound for acoustic waves. In simple terms, wavelength is the distance between successive crests of a wave, while frequency is the number of waves that pass a point in one second.

Mathematically, this relationship is expressed by the formula:

$c=\lambda \times f$

where c is the speed of the wave (speed of light in a vacuum is approximately 3 × 10⁸ meters per second), λ (lambda) is the wavelength, and f is the frequency.

As the frequency of a wave increases, its wavelength decreases, and vice versa. For example, in the electromagnetic spectrum, red light has a longer wavelength and lower frequency compared to blue light, which has a shorter wavelength and higher frequency. This principle is crucial in understanding the behavior of waves across different mediums and applications, such as in telecommunications, astronomy, and physics.

What is the amplitude of a wave?

The amplitude of a wave is a measure of its maximum disturbance from its undisturbed or rest position. In simpler terms, it's the height of the wave crest or the depth of the trough from the equilibrium position. In a visual sense, if you imagine a wave on a string or a water wave, the amplitude is the distance from the midpoint of the wave to the top of a crest or to the bottom of a trough.

Amplitude is an important characteristic of a wave as it's directly related to the energy carried by the wave. The greater the amplitude, the more energy the wave is transporting. In the case of sound waves, amplitude is related to the volume or loudness of the sound; a larger amplitude means a louder sound. For electromagnetic waves, like light, the amplitude is associated with the intensity or brightness of the light.