4. In order to see objects, the wavelength of the light must be smaller than the object. The Bohr radius of a hydrogen atom is 5.291 77 x 10–11 m. a. What is the lowest frequency that can be used to locate a hydrogen atom? b. The visible part of the spectrum ranges from 400 nm to 700 nm. Why aren’t individual atoms visible? 6. Suppose you must decide whether a pre-Columbian mask is genuine before buying it for a museum. It looks genuine, but to ensure its authenticity, you shine X rays of wavelength 1.67x10–10 m on it to see if a certain element is present. What is the frequency of this radiation?

7. Suppose you use ultraviolet light of frequency 9.5x1014 Hz to determine whether a mineral is fluorescent. To what wavelength does this correspond?

8. Meteorologists use Doppler radar to watch the movement of storms. If a weather station uses electromagnetic waves with a frequency of 2.85x109 Hz, what is the length of the wave?

9. PCS cellular phones have antennas that use radio frequencies from 1800–2000 MHz. What range of wavelengths corresponds to these frequencies?
10. Suppose the microwaves in your microwave oven have a frequency of 2.5x 1010 Hz. a. What is the wavelength of these microwaves?
b. The holes in the door of a microwave oven have a radius of 1.2 mm. Why don’t microwaves pass through these holes?
c. Visible light has a wavelength that ranges from 400 nm to 700 nm. Would visible light be able to pass through the holes? Why or why not?