Microwaves are considered to be waves in the electromagnetic spectrum of lengths from 1MM to 1m.
On average, microwave ovens have a frequency of 2450MHz, which corresponds to a wavelength of about 12cm.
In your microwave oven, the machine creates a standing electromagnetic wave of about 12cm in length, which can be understood with the graph:
In actuality, though, EM waves are both photon particles and waves! That is, each wavelength is a 'separate photon'. Considering them as waves works to explain their behaviour most of the time, so just think of them as waves for now.
Anyway, these standing waves interact with molecules in your food (pretty well with water due to its dipole-dipole) and heats it up. I'm not going in-depth about this as it's a whole different topic on quantum/particle physics.
If we stop the microwave from spinning our food around and leave something in there then the food will only be heated where the antinodes are:
The nodes are where there is a interference that cancels the waves, thus there is no interaction between the wave and molecules. That means that your object in the microwave will be heated where the antinodes are and not heated where the nodes are!
Knowing this we can place just about anything that changes texture when heated in the microwave and stop it from spinning to detect exactly where it is being heated.
Examples are cheese evenly spread out in a container, a long chocolate bar.
What I did was 'paint' a flat surface with tomato sauce evenly and put it in the microwave for under 10s as the sauce is quickly heated and dried where the antinodes are.
I then measured the distance between the center of each burning line and found it to be about 6cm. Known this is the distance between each anti node, the wavelength is therefore twice that, about 12cm as expected!
Now to calculating the speed of light;
We know that speed is the change in distance per time, which is mathemtically represented as
s= d / t
In this case we will be measuring how many METRES are covered per 1 SECOND of time, m / s.
The wavelenght of the EM wave is therefore the distance, so if we measure the period of the wave, that is how long it takes for a full oscillation, we can find the distance covered per time
thus speed = wavelength / period
since period, T (time) = how many seconds it takes for a full oscillation, that is a full wavelength is distance to complete, then T = time / wavelength
frequency on the other hand, is the opposite of period; it is defined as the amount of wavelengths complete per second, f = wavelength / time
Since frequency and period are opposite, we can represent this mathemtically as
f= 1/ T
T = 1 / f
back to s = d / t = wavelength / T
plug in f
wavelength / 1/T
simplifies to
wavelength x T = speed
and now we get the famous equation v = fλ
we need to use frequency in the formula because that's the information that our microwave ovens give us. Since we know the speed of light is a constant, about 299 792 458 m / s in a vaccuum, we can calculate the wavelength and predict the distance
then u find the distance between burning spots in your food and it should be 1/2 of the wavelength calculated fromt he frequency of your microwave oven. by changing the frequency of your microwave oven we can change that distance.
MAGIC!
TO BE EDITED INTO BETTER EXPLANATION AFTER HSC
On average, microwave ovens have a frequency of 2450MHz, which corresponds to a wavelength of about 12cm.
In your microwave oven, the machine creates a standing electromagnetic wave of about 12cm in length, which can be understood with the graph:
Anyway, these standing waves interact with molecules in your food (pretty well with water due to its dipole-dipole) and heats it up. I'm not going in-depth about this as it's a whole different topic on quantum/particle physics.
If we stop the microwave from spinning our food around and leave something in there then the food will only be heated where the antinodes are:
Knowing this we can place just about anything that changes texture when heated in the microwave and stop it from spinning to detect exactly where it is being heated.
Examples are cheese evenly spread out in a container, a long chocolate bar.
What I did was 'paint' a flat surface with tomato sauce evenly and put it in the microwave for under 10s as the sauce is quickly heated and dried where the antinodes are.
I then measured the distance between the center of each burning line and found it to be about 6cm. Known this is the distance between each anti node, the wavelength is therefore twice that, about 12cm as expected!
Now to calculating the speed of light;
We know that speed is the change in distance per time, which is mathemtically represented as
s= d / t
In this case we will be measuring how many METRES are covered per 1 SECOND of time, m / s.
The wavelenght of the EM wave is therefore the distance, so if we measure the period of the wave, that is how long it takes for a full oscillation, we can find the distance covered per time
thus speed = wavelength / period
since period, T (time) = how many seconds it takes for a full oscillation, that is a full wavelength is distance to complete, then T = time / wavelength
frequency on the other hand, is the opposite of period; it is defined as the amount of wavelengths complete per second, f = wavelength / time
Since frequency and period are opposite, we can represent this mathemtically as
f= 1/ T
T = 1 / f
back to s = d / t = wavelength / T
plug in f
wavelength / 1/T
simplifies to
wavelength x T = speed
and now we get the famous equation v = fλ
we need to use frequency in the formula because that's the information that our microwave ovens give us. Since we know the speed of light is a constant, about 299 792 458 m / s in a vaccuum, we can calculate the wavelength and predict the distance
then u find the distance between burning spots in your food and it should be 1/2 of the wavelength calculated fromt he frequency of your microwave oven. by changing the frequency of your microwave oven we can change that distance.
MAGIC!
TO BE EDITED INTO BETTER EXPLANATION AFTER HSC