in chapter 32 section 4 on electromagnetic waves, near the end he writes since [itex] \lambda = \frac{2\pi c}{\omega}[/itex] then [itex]\Delta\lambda = \frac{2 \pi c \Delta \omega}{{\omega}^2}[/itex]. i understand the first equation he writes but then the second one i am having trouble convincing myself how he came up with that.(adsbygoogle = window.adsbygoogle || []).push({});

also earlier in chapter 30 on refraction, he also says the frequency is [itex] \nu = \frac{c}{\lambda} [/itex] so [itex] \Delta \nu = \frac{c \Delta \lambda}{{\lambda}^2} [/itex]. similarly i don't understand how he comes up with the second equation. he doesn't seem to explain it and it's not obvious to me how he got that. can someone help clarify this? thanks!

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# Question on feynman lectures volume 1 (wavelength and frequency)

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