1. Identify which portions of the electromagnetic spectrum are used in each of the devices listed. a. a microwave oven b. a television set C. a single-lens reflex camera 2. If an electromagnetic wave has a frequency of 7.57 x 10 * Hz, what is its wavelength? To what part of the spectrum does this wave belong? 3. Galileo performed an experiment to measure the speed of light by timing how long it took light to travel from a lamp he was holding to an assistant about 1.5 km away and back again. Why was Galileo unable to conclude that light had a finite speed? Critical Thinking 4. How bright would the sun appear to an observer on Earth if the sun were four times farther from Earth than it actually is? Express your answer as a fraction of the sun's brightness on Earth's surface