A "night light" illuminates dark hallways and children's rooms at night. Older night lights use incandescent bulbs (tungsten filament in an evacuated glass envelope), while newer night lights use light-emitting diodes (LEDs). The older style night light bulb requires 4 W of power to operate, while a newer LED night light might require about 0.2 W of power. According to the U.S. Department of Energy, a kilowatt-hour costs 9.85 cents for the residential customers, on average (http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html).

During the course of a year, what is the total cost saved by using an LED-based night light instead of the older style night light?

As of 1983, the definition of a "meter" is based on the speed of light, specifically, the distance that light travels in a vacuum during the time interval 299,792,458^-1 seconds. Electrical signals moving in a cable (for example, the coaxial cable that connects your television to the cable jack in the wall) travel at approximately 70% of the speed of light. Speaking of television, a high-definition (HD) receiver can update its display 60 times per second, where each display frame contains 1280x720 pixels.

So: How far can the television signal travel in a coaxial cable during the time that an HD receiver is drawing a new pixel on the screen?

Beginning in Beijing, China, you need to travel about 11,000 kilometers to reach New York City. Communication satellite signals traveling between these two cities move at close to the speed of light (3x10⁸ meters per second). The eye blink duration of a human is approximately 300 milliseconds. So, is it possible for a communication signal to jump from Beijing to New York in the "blink of an eye?"