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Electromagnetic Waves - Section 14A

 

1. New-generation cordless phones use a 9.00 D102 MHz frequency and can be operated up to 60.0 m from their base. How many wavelengths of the electromagnetic waves can fit between your ear and a base 60.0 m away?

2. The highest directly measured frequency is 5.20 D1014 Hz, corresponding to one of the transitions in iodine-127. How many wavelengths of electromagnetic waves with this frequency could fit across a dot on a book page? Assume the dot is 2.00 D10-4 m in diameter.

3. Commercial trucks cause about 18 000 lane-change and merging accidents per year in the United States. To prevent many of them, a warning system covering blind spots is being developed. The system uses electromagnetic waves of frequency 2.40 D1010 Hz. What is the wavelength of these waves?

4. A typical compact disc stores information in tiny pits on the discís surface. A typical pit size is 1.2 mm. What is the frequency of electromagnetic waves that have a wavelength equal to the typical CD pit size?

5. A new antiterrorist technique detects the differences in electromagnetic waves emitted by humans and by weapons made of metal, plastic, or ceramic. One possible range of wavelengths used with this technique is from 2.0 mm to 5.0 mm. Calculate the associated range of frequencies.

6. The U.S. Armyís loudest loudspeaker is almost 17 m across and is transported on a special trailer. The sound is produced by an electromagnetic coil that can generate a minimum frequency of 10.0 Hz. What is the wave- length of these electromagnetic waves?

 

 Answers