Textbook Problem 1A.3


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SophiaNguyen_2E
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Joined: Wed Sep 30, 2020 9:59 pm

Textbook Problem 1A.3

Postby SophiaNguyen_2E » Sat Oct 24, 2020 10:23 pm

Hello! So the question is:

Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning.
(a) The speed of the radiation decreases.
(b) The wavelength of the radiation decreases.
(c) The extent of the change in the electrical field at a given point decreases.
(d) The energy of the radiation increases.

I'm pretty sure the right answer is C, but I wanted to understand why A isn't the right answer. Can someone explain the relationship between the speed of radiation and frequency/wavelength? Thank you in advance!

Jaden Joodi 3A
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Re: Textbook Problem 1A.3

Postby Jaden Joodi 3A » Sat Oct 24, 2020 10:36 pm

I am fairly certain that there is no relationship between the frequency/wavelength of electromagnetic radiation, and the speed at which it moves. This is because electromagnetic radiation moves at a constant speed of 3.0 x 10^8 m/s in a vacuum. This is how we get the formula c= wavelength * frequency.

Kyla Roche 2D
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Re: Textbook Problem 1A.3

Postby Kyla Roche 2D » Sat Oct 24, 2020 10:41 pm

Frequency has a direct relationship with Energy however not with speed because speed if a constant (c)

Daniela_Martinez_3B
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Re: Textbook Problem 1A.3

Postby Daniela_Martinez_3B » Sat Oct 24, 2020 10:41 pm

Any electromagnetic wave's frequency multiplied by its wavelength equals the speed of light. The speed of light is always 3x10^8!

Tae Pasawat 2A
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Re: Textbook Problem 1A.3

Postby Tae Pasawat 2A » Sun Oct 25, 2020 12:34 am

Can someone please explain part C? Thank you!

Megan Lu 3B
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Re: Textbook Problem 1A.3

Postby Megan Lu 3B » Sun Oct 25, 2020 1:25 am

^ Hi! I believe the correct answer should be C because frequency in EM radiation refers to the number of cycles that occur within a given amount of time. If the frequency decreases, there are fewer cycles taking place in this interval of time and the waves broaden. Thus, the extent of change that happens decreases. Hope this makes sense.

Veeda Khan 2E
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Joined: Wed Sep 30, 2020 10:00 pm

Re: Textbook Problem 1A.3

Postby Veeda Khan 2E » Sun Oct 25, 2020 10:01 am

Tae Pasawat 2A wrote:Can someone please explain part C? Thank you!


Another way to think of it is that the peaks of the waves are further apart, so the "slope" of the waves are less, thus a decrease of change between points.

Edwin Liang 2I
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Re: Textbook Problem 1A.3

Postby Edwin Liang 2I » Sun Oct 25, 2020 5:08 pm

Since frequency and wavelength are directly related to one another( c = λ * v ), the slope on a wave with high frequency will be more than that with a lower frequency. This means the "extent of change" (slope) decreases as frequency decreases.

jasmineculilap_2J
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Re: Textbook Problem 1A.3

Postby jasmineculilap_2J » Sun Oct 25, 2020 5:10 pm

Speed of light in a vacuum is constant where c = 3.00 * 10^8. c can also be found by c = λ * v, so frequency and wavelength are inversely related.

KKrivenko_3J
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Re: Textbook Problem 1A.3

Postby KKrivenko_3J » Sun Oct 25, 2020 5:13 pm

Choice A isn't the right answer because the speed of radiation is always constant and equal to the speed of light ( m/s). Therefore, as frequency decreases, the wavelength increases, so that their product would always be equal to the speed of light. Hope this helps :)


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