They only differ from each other in wavelength. Wavelength is the distance between one wave crest to the next. Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom. Yet their size can be related to their energy. The smaller the wavelength the higher the energy. For example, a brick wall blocks visible light wave lengths.
Smaller, more energetic, x-rays can pass through brick walls, but themselves are blocked by denser material such as lead. While it can be said waves are "blocked" by certain materials, the correct understanding is that wave lengths of energy are "absorbed" by objects, or not. That is, wave length energy can be absorbed by certain material. The beauty of a coral reef, the warm radiance of sunshine, the sting of sunburn, the X-ray revealing a broken bone, even microwave popcorn—all are brought to us by electromagnetic waves.
Even more intriguing is that all of these widely varied phenomena are different manifestations of the same thing—electromagnetic waves. See Figure 2.
What are electromagnetic waves? How are they created, and how do they travel? How can we understand and organize their widely varying properties? What is their relationship to electric and magnetic effects? These and other questions will be explored. You are commenting using your Google account. You are commenting using your Twitter account.
You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. May 24, March 29, xcorr. I was reading the Wikipedia article on tinnitus , and came across this pearl of a sentence: A common and often misdiagnosed condition that mimics tinnitus is Radio Frequency RF Hearing in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus. Photoacoustic effect. When lasers pulses are transported into a sample a , they can get absorbed by an inclusion.
This causes thermal expansion, which creates sound waves b , which can then be captured by detectors. RF hearing is hypothesized to be caused by a similar phenomenon, but with the energy source being radio-frequencies rather than visible light. Like this: Like Loading Leave a comment Cancel reply Enter your comment here And although the claim hasn't held up under scrutiny, that was perhaps not entirely nutty; the most severe symptoms of ultrasonic-wave exposure do include headaches, tinnitus and hearing loss similar to what the U.
Leighton, like most scientists, is skeptical that ultrasonic weapons were actually involved in that event. In reality, Leighton said, the reason ultrasonics are a problem is not that in bizarre, extreme cases they might expose a tiny fraction of the population to brain or permanent hearing damage.
Rather, ultrasonics are likely exposing a large, young, vulnerable fraction of the population to discomfort, annoyance and the stigma of hearing things others can't. And all that could easily be avoided. Back in the late s and early '70s, researchers for the first time systematically examined what sort of sounds could cause problems in the workplace but were high-pitched enough that they didn't become problematic in limited, low-volume doses. Based on those studies, governments around the world arrived at a common guideline for ultrasonics in the workplace: 20 kilohertz at medium volumes, or 20, vibrations per second.
That's a very high-pitched sound — much higher than most adults can hear. In the video below, a tone slowly rises from a superlow hertz tone to a 1,times-higher 20 kilohertz. I'm a year-old man, and I can't hear anything once the tone rises past about 16 kilohertz. But I can't say for certain that this isn't the result of my headphones maxing out, rather than my hearing.
But it's not too high for all humans to hear. Just about everyone loses some hearing at the high end of the spectrum as they age. Anyone who was in high school in the late s will likely remember the annoying "mosquito" ringtone that teenagers could hear but teachers generally could not.
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