A standard cell phone transmitselectromagnetic waves with afrequency of $1.90\times10^9Hz$ .Calculatethewavelengthof these electromagnetic waves (in cm).

Who will hear the voice of a singer first: a person in the balcony 50.0 km away from the stage (see Fig. 31–26), or a person 1800 km away at home whose ear is next to the radio listening to a live broadcast? Roughly how much sooner? Assume the microphone is a few centimeters from the singer and the temperature is 20℃.

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Estimate the wavelength for a 1.9-GHz cell phone transmitter.

If the Sun were to disappear or radically change its output, how long would it take for us on Earth to learn about it?

(I) What is the range of wavelengths for (a) FM radio (88 MHz to 108 MHz) and (b) AM radio (535 kHz to 1700 kHz)?

(I) An EM wave has frequency 2.65 x 10¹⁴ Hz. What is its wavelength, and how would we classify it?

(III) Stars located in a certain cluster are assumed to be about the same distance from us. Two such stars have spectra that peak at λ₁ = 470nm and λ₂ = 720 nm, and the ratio of their apparent brightness is b₁/b₂ = 0.091. Estimate their relative sizes (give ratio of their diameters) using Wien’s law and the Stefan-Boltzmann equation, Eq. 19–17.

In free space (“vacuum”), where the net charge and current flow is zero, the speed of an EM wave is given by v = 1 √(ε₀μ₀). If, instead, an EM wave travels in a nonconducting (“dielectric”) material with dielectric constant K, then v = 1 √(Kε₀μ₀). For frequencies corresponding to the visible spectrum (near 5 x 10¹⁴ Hz), the dielectric constant of water is 1.77. Predict the speed of light in water and compare this value (as a percentage) with the speed of light in a vacuum.