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Celeste Martinez 1K
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HW 1.5

Postby Celeste Martinez 1K » Thu Apr 12, 2018 3:00 am

The homework problem asks us to "arrange the following types of photons of electromagnetic radiation in order of increasing energy: y-rays, visible light, ultraviolet radiation, microwaves, x-rays"
Are we suppose to look at an image/chart in order to figure this out or are we suppose to calculate the energy on our own?

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Re: HW 1.5  [ENDORSED]

Postby nelquosey » Thu Apr 12, 2018 9:45 am

To calculate anything about frequency or energy you would need to be given wavelength. This question is testing general knowledge of electromagnetic radiation. The question assumes that you know the order.

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Re: HW 1.5

Postby EllenRenskoff-1C » Thu Apr 12, 2018 10:48 am

The answer key says that gamma rays have the highest energy, though in table 1.1 on pg. 4 it did not seem like there was enough information to distinguish whether x-rays or gamma rays have higher energy. How would we figure out which one has the higher amount of energy in a problem that's more general like this one?

Caitlyn Ponce 1L
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Re: HW 1.5

Postby Caitlyn Ponce 1L » Thu Apr 12, 2018 8:35 pm

I also had the same question. X-rays and gamma rays have identical information in the previously mentioned table and I'm not sure how to differentiate the two.

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Re: HW 1.5

Postby AnthonyDis1A » Fri Apr 13, 2018 11:01 am

The textbook table is technically correct since the energy potential of both waves have a lot of overlap. However, one can differentiate the two conceptually: gamma rays are nuclear in origin, whereas X-rays have an electronic source. I guess the solution ranked gamma radiation as higher in energy than X-rays because most gamma radiation examples (i.e. nucleus decay) are harnessed more frequently, man-made or not, and inflict actual/potential destruction (i.e. bombs or spontaneous solar eruptions). (?)

Jacy Black 1C
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Re: HW 1.5

Postby Jacy Black 1C » Sat Apr 14, 2018 1:08 pm

I had the same question for 1.5. I think the key is the combination of two things: the table on pg. 4 as someone else noted above, and the table on pg.6 showing the electromagnetic spectrum and the range of wavelengths. While table 1.1 on page 4 differentiates different energy levels for most of the different waves of light, it doesn't differentiate between the energy levels for X-rays and "v"-rays. Figure 1.9 on page 6 shows the wavelengths of the different light waves. If you remember,

-energy is proportional to the frequency, and therefore energy has an inverse relationship to the wavelength.

Figure 1.9 shows the wavelengths, differentiating between the X-rays and the "v"-rays. With the knowledge that the higher energy light wave is the one with the shortest wavelength, it is clear that the v-rays have the highest energy.

I hope this helps!

Joanna Pham - 2D
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Re: HW 1.5

Postby Joanna Pham - 2D » Sat Apr 14, 2018 11:58 pm

If we were given a question like this on a test, will we be expected to remember where each category falls on the electromagnetic spectrum?

Also, why is it that Energy = (wavelength)*(frequency)? This appears to follow the equation given in the book, c=(wavelength)*(frequency), but why isn’t c being used here? We are given the value of c, but I don’t see why you could change it to calculate the energy of something such as the UV rays..

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Re: HW 1.5

Postby Chem_Mod » Sun Apr 15, 2018 7:04 pm

You should familiarize with the relative order of the different types of electromagnetic waves.

With regards to confusion of x-rays and gamma-rays, gamma-rays have the higher frequency and the higher energy of the two.

Energy of a photon = h*frequency

c = wavelength*frequency.

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