A common electromagnet consists of a

If an object absorbs more energy than it emits, its

The temperature at the bottom of Lake Tahoe, high in the Sierra Mountains in California, at this moment is

Hydrothermal vents deep beneath the ocean surface attain temperatures far above 100°C due to

Fourier analysis is used

A transformer for a laptop computer converts a 120-V input to a 24-V output. Compared with the number of turns on the primary coil, the secondary has

A mixture of cyan and yellow inks on a printed page appears

Disregarding the effects of friction, a cyclist will coast farther when a lamp powered by a wheel generator is

A blue object will appear black when illuminated with

Poke a pinhole in a piece of card and hold it in sunlight and an image of the Sun is cast on the floor. The Sun-image diameter depends on the height of the pinhole above the floor. Measurements for all heights show the Sun-image diameter is about 1/100 the distance between the pinhole and the floor. This means that