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HW2-Chapter 21 1. If the Sun suddenly turned off, we would not know it until its

ID: 1732023 • Letter: H

Question

HW2-Chapter 21 1. If the Sun suddenly turned off, we would not know it until its light stopped coming. How long would that be, given that the Sun is 1.50x10 m away? 2. Find the wavelength for (a) a typical AM radio wave with a frequency of 1000 kHz and (b) a typical FM radio wave of 100 MHz. 3. What is the frequency of a 3-cm microwave? 4. What is the frequency of an X ray with a wavelength of 0.1 nm? 5. What is the maximum strength of the B-field in an electromagnetic wave that has a maximum E -field strength of 1000 V/m? 6. Calculate the wavelengths of a 1530-kHz AM radio signal, a 105.1-MHz FM radio signal, and a 1.90-GHz cell phone signal.

Explanation / Answer

1) time taken = distance / speed

= 1.5*10^11 / 3*10^8

= 500 s

2) wavelength = speed of light / frequency

a) 3*10^8 / 1000*1000

= 300 m

b) 3*10^8 / 100*10^6

= 3 m