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What’s the Difference Between EMF Energy and Power?

While they are often used interchangeably, EMF energy and power mean very different things.

EMF Spectrum

First, it is important to understand that there is a broad spectrum of electromagnetic radiation, as we can see in this diagram.

The Electromagnetic Spectrum, EMF energy and power
The Electromagnetic Spectrum

On the left, we see extremely low frequency (or ELF), which is the lowest frequency of electromagnetic radiation. And on the right, we see gamma rays, which is very high frequency form of electromagnetic radiation. Roughly in the middle, we see visible light, such as emitted by the sun and light bulbs.

EMF Frequency

What distinguishes each type of EMF radiation is the frequency at which the EMF waves vibrate. EMF waves are just like waves you see in the ocean. Sometimes they’re slower and less frequent, and sometimes they’re faster. This frequency of the EMF waves is usually measured in hertz (Hz). 1 hertz is equal to one cycle (or, one wave) per second. The lower the frequency, the lower the hertz (or the fewer waves per second); the higher the frequency, the higher the hertz (or the more waves per second).

You’ve probably heard of these units before. For example, maybe you heard that electricity in the United States operates at 60 Hz (and in most of the rest of the world, it’s 50 Hz). Or maybe you have a 2.4 gigahertz (GHz) cordless phone, or a 5 GHz WiFi router. That’s referring to the frequency of the EMF radiation used by these technologies. The higher the hertz value of a technology, the higher the frequency of the EMF it uses and/or emits.

Higher Frequency in the EM Spectrum

EMF Energy

Now that you understand what EMF frequency is, it’s really easy to understand what ‘energy’ means in the context of EMF. Energy refers to the frequency. The higher the frequency, the higher the energy. So your WiFi router emits more energy than your refrigerator, and visible light from the sun is a higher form of energy than WiFi. If you look back up at the diagram of the EMF spectrum, the further you go to the right, the more energy that form of EMF has.

Higher Energy in the EM Spectrum

The energy level is also what determines the difference between ionizing and non-ionizing forms of EMF radiation. All EMF with more energy than visible light (i.e., to the right of visible light on the EMF spectrum) is called ionizing radiation (so-called because that EMF has enough energy to ionize, or knock electrons loose from, your cells). And all EMF with less energy than visible light (i.e., to the left of visible light on the spectrum) is called non-ionizing radiation, because the energy level is insufficient to ionize your cells.

EMF Power

Ok, that’s what energy means. So what does power mean?

While energy refers to the frequency of the EMF radiation, power refers to how strong that EMF radiation is.

EMF Spectrum, Power vs. Energy

Let’s take wireless communication as an example. Let’s say your cell phone is having trouble making a connection to the cell tower to relay your phone call. In that case, your phone will boost the amount of power it’s using for its transmission, so that it tries harder to make the connection. That makes sense, right? Because if your phone is having trouble connecting to the cell tower, your phone needs to try harder, and emit a stronger signal, to make that connection happen. You cell phone doesn’t need to change it’s frequency, or energy level; but it does need to emit more power.

Or let’s say you have a pair of bluetooth headphones. Because your headphones only need to communicate with your phone (which is likely within 30 feet of your headphones), those bluetooth headphones are emitting much less power than your cell phone, because those headphones don’t have to try that hard to make that connection.

In those examples, the amount of power of the EMF emissions changes, while the energy level stays the same.

What Does This Have To Do with My Personal Health?

So what does all this have to do with helping to understand the health risk of EMF exposure? Well, to start, higher-energy ionizing EMF radiation is known to be very dangerous, even at extremely low dosages. That’s why you wear sunblock when you’re outside, and why it’s recommended to get as few x-rays as possible when you’re at the doctor or dentist.

The question becomes more contested when we discuss the lower energy non-ionizing forms of EMF radiation, such as radio frequency and microwaves used for wireless communications. And this is where the notion of power becomes more important to consider.

Because, as anyone who has used a microwave oven knows, microwaves (which are a lower-energy non-ionizing form of EMF, the same type of EMF used by cell phones and WiFi to communicate) can cook food– and human tissue– but only at very high levels of power. This is called the ‘thermal effect‘ of EMF, where powerful enough non-ionizing forms of EMF radiation can heat tissue and damage and destroy your DNA. And this is what all EMF emission regulations in the United States are based on.

The FCC wants to ensure that your cell phone doesn’t emit microwaves powerful enough to heat your tissue. In other words, the FCC just wants to make sure that your cell phone— or WiFi router or wearable device— isn’t literally cooking you. (But even that benchmark isn’t really fully enforced, as this video shows.)

It was long assumed that lower-energy non-ionizing forms of EMF radiation at power levels insufficient to heat your tissue are inert– that is, they can not impact human health. But over the past decades, an increasingly large body of high quality, peer-reviewed scientific evidence has emerged demonstrating that even at very low levels of power, low-energy non-ionizing EMF radiation (such as is emitted by your WiFi router, cell phone, and power lines) can, over the long term, result in significant negative health effects.

Regardless of whether you accept the growing body of science that demonstrates these negative bioeffects, as you can see, to be informed about EMF radiation and participate in the discussion, it is very important to understand the difference between EMF energy and power. 

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