1. Your alarm clock has a sound level of 80 dB, but it fails to wake you up. You want it to sound louder so that it might wake you up. To sound twice as loud, the alarm must deliver ten times the energy to your eardrums, and that means it needs a new sound level of how many decibels?

2. The visible spectrum of light is often given in terms of the wavelengths of the various colors, with the range of wavelengths for visible light traveling through air being approximately from 400 to 700 nm. For light of wavelength 471 nm, find its frequency to the nearest terahertz.

3. When lightning strikes, it causes air to become heated to an extremely high temperature in a short amount of time, rapidly expanding the air. This explosive expansion is the source of thunder. The light from the lightning travels in air at 3 × 108 m/s and the sound of the thunderclap travels in air at 343 m/s. If you are standing 6600 m away from the storm, approximately how much time passes between you seeing the flash of lightning and you hearing the sound of thunder? Round to the nearest second.