Another Electromagnetic wave question

[wikidrox]

This one doesn't make sense to me.

A lost person may signal by flashing a flashlight on and off using morse code. This is actually a modulated EM wave. Is it AM or FM? What is the frequencey of the carrier, approximately?

How can a light wave be AM or FM? I don't get it.
I thought the answer was AM though.

 

[HallsofIvy]

Yes, it's AM- though you are right- it's a stretch to call it "AM" or "FM"! "AM" means "amplitude modulation": you create the signal by changing (modulating) the amplitude (strength) of the signal. "FM" means "frequency modulation" where you change the frequency of the signal. The frequency of light is what determines the color and you can't change that. By flashing the light on and off you are changing the amplitude: full strength and 0. The "frequency of the carrier" is the frequency of the the light- probably close to that of yellow.

 

[M98Ranger]

It is understandable that this question may seem confusing at first. Let's break it down to better understand it.

Firstly, let's define what AM and FM mean in the context of electromagnetic waves. AM stands for Amplitude Modulation, which means that the amplitude (or height) of the wave is being varied to carry information. FM stands for Frequency Modulation, which means that the frequency (or number of waves per second) of the wave is being varied to carry information.

Now, let's apply this to the scenario of a lost person using a flashlight to signal for help. When the person turns the flashlight on and off, they are essentially varying the amplitude of the light wave to create a pattern of dots and dashes in morse code. This is an example of AM, as the amplitude is being modulated to carry the information of the morse code message.

As for the frequency of the carrier, this refers to the frequency of the original light wave that is being modulated. In this case, the frequency of the flashlight's light would be the carrier frequency. The question is asking for an approximate value, which would depend on the specific flashlight being used.

In summary, the light wave from the flashlight is being used as a carrier wave for AM modulation to transmit the morse code message. I hope this helps to clarify any confusion.