Loesje22000 Posted November 21, 2017 Share Posted November 21, 2017 Question of dd: If definition 1 says: Speed = distance travelled / time taken Definition 2 says: Speed = frequency x wavelength Is one allowed to say: Distance travelled / time taken = frequency x wavelength. ????? Quote Link to comment Share on other sites More sharing options...
Arcadia Posted November 21, 2017 Share Posted November 21, 2017 (edited) Assuming we are taking about the same wave, you could equate those two equations and solve for the unknown. Definition 1 “The speed (or sometimes you might see it called velocity) of a wave, v, is how far the wave travels in a certain time. Wave speed is measured in metres per second (m/s). All the electromagnetic waves travel at 300,000,000 metres per second (3 x 108 m/s). Sound travels at about 340 metres per second.†http://www.bbc.co.uk/bitesize/standard/physics/telecommunications/communication_using_waves/revision/5/ Definition 2 is the wave equation “Wave Speed = Frequency x Wavelength v = f x λ Where: Wave speed is in metres per seconds (m/s or ms-1) Frequency is in Hertz (Hz). Wavelength is in metres (m). NB: It should be noted that some particular waves have their own specific speeds. The speed of light and all of the EM spectrum is 300,000,000 m/s or 3x108 m/s. The speed of sound in air is 340 m/s.†http://www.bbc.co.uk/bitesize/intermediate2/physics/waves_and_optics/wave_equation/revision/1/ It is 10 to the power of 8 in the BBC quotes above, don’t know how to do superscript on phone. ETA: Look at question 4 & 5 of the UK paper http://www.ocr.org.uk/Images/409054-question-paper-unit-g482-01-electrons-waves-and-photons.pdf Scoring guideline http://www.ocr.org.uk/Images/410706-mark-scheme-unit-g482-electrons-waves-and-photons-june.pdf Edited November 21, 2017 by Arcadia 1 Quote Link to comment Share on other sites More sharing options...
regentrude Posted November 21, 2017 Share Posted November 21, 2017 (edited) If definition 1 says: Speed = distance travelled / time taken Definition 2 says: Speed = frequency x wavelength Is one allowed to say: Distance travelled / time taken = frequency x wavelength. Yes, for a traveling wave, the distance the wave travels per time, i.e. the wave speed, is exactly frequency times wave length. A traveling wave travels one complete wavelength during one period. The period is the inverse of the frequency. Please note that the wave speed is NOT the speed of a particle in the medium! The wave speed is the speed with which a crest of the wave moves along the medium. let me know if she has more questions. Edited November 21, 2017 by regentrude 2 Quote Link to comment Share on other sites More sharing options...
Loesje22000 Posted November 21, 2017 Author Share Posted November 21, 2017 Assuming we are taking about the same wave, you could equate those two equations and solve for the unknown. Definition 1 “The speed (or sometimes you might see it called velocity) of a wave, v, is how far the wave travels in a certain time. Wave speed is measured in metres per second (m/s). All the electromagnetic waves travel at 300,000,000 metres per second (3 x 108 m/s). Sound travels at about 340 metres per second.â€http://www.bbc.co.uk/bitesize/standard/physics/telecommunications/communication_using_waves/revision/5/ Definition 2 is the wave equation “Wave Speed = Frequency x Wavelength v = f x λ Where: Wave speed is in metres per seconds (m/s or ms-1) Frequency is in Hertz (Hz). Wavelength is in metres (m). NB: It should be noted that some particular waves have their own specific speeds. The speed of light and all of the EM spectrum is 300,000,000 m/s or 3x108 m/s. The speed of sound in air is 340 m/s.†http://www.bbc.co.uk/bitesize/intermediate2/physics/waves_and_optics/wave_equation/revision/1/ It is 10 to the power of 8 in the BBC quotes above, don’t know how to do superscript on phone. ETA: Look at question 4 & 5 of the UK paperhttp://www.ocr.org.uk/Images/409054-question-paper-unit-g482-01-electrons-waves-and-photons.pdf Scoring guidelinehttp://www.ocr.org.uk/Images/410706-mark-scheme-unit-g482-electrons-waves-and-photons-june.pdf Yes, for a traveling wave, the distance the wave travels per time, i.e. the wave speed, is exactly frequency times wave length. A traveling wave travels one complete wavelength during one period. The period is the inverse of the frequency. Please note that the wave speed is NOT the speed of a particle in the medium! The wave speed is the speed with which a crest of the wave moves along the medium. let me know if she has more questions. Thank you both!!! She asked me a few pages before a similar question, and today again, and I just wastn’t sure it was allowed :) For now she understands this, but I will definetly post any further questions, thanks in advance! Quote Link to comment Share on other sites More sharing options...
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