#4 #10 #144. The voltage in the lines that carry electric power to homes is typically 20,000 Volts. What is the ratio of the turns in the primary and secondary coils of the transformer required to drop the voltage to 120 Volts?
Recalling that the voltage divided by the number of turns in the coil for that voltage is constant, we write
10. An x-ray machine has a peak wavelength of 3 Angstroms. What is the peak frequency?
We solve this exercise by using the relationship that the speed of a wave (in this case the speed of light denoted by c) is equal to the wave's frequency times its wavelength.
14. What is the range of wavelengths for FM radio?
The frequency range for FM radio waves is given as 88 MHz to 108 MHz at the top of page 511 in the textbook. With this, we immediately write the solution as follows:
