                               Q&A: Electromagnetic spectrum      Page: 1  2    Next...  Light, color, and the electromagnetic spectrum See chart below 1. What is the electromagnetic spectrum?   2. What is a light wave? Light is a disturbance of electric and magnetic fields that travels in the form of a wave. Imagine throwing a pebble into a still pond and watching the circular ripples moving outward. Like those ripples, each light wave has a series of high points known as crests, where the electric field is highest, and a series of low points known as troughs, where the electric field is lowest. The wavelength is the distance between two wave crests, which is the same as the distance between two troughs. The number of waves that pass through a given point in one second is called the frequency, measured in units of cycles per second called Hertz. The speed of the wave therefore equals the frequency times the wavelength.  3. What is the relationship between frequency and wavelength? Wavelength and frequency of light are closely related. The higher the frequency, the shorter the wavelength. Because all light waves move through a vacuum at the same speed, the number of wave crests passing by a given point in one second depends on the wavelength. That number, also known as the frequency, will be larger for a short-wavelength wave than for a long-wavelength wave. The equation that relates wavelength and frequency is: For electromagnetic radiation, the speed is equal to the speed of light, c, and the equation becomes:   4. What is the relationship between wavelength, frequency, and energy? The energy of a wave is directly proportional to its frequency, but inversely proportional to its wavelength. In other words, the greater the energy, the larger the frequency and the shorter (smaller) the wavelength. Given the relationship between wavelength and frequency described above, it follows that short wavelengths are more energetic than long wavelengths. Electromagnetic spectrum Page: 1  2    Next...   Q&A: Electromagnetic spectrum   