Illinois State University PHY 102 Final Exam Study Guide | 120 Questions with 100% Correct Answers | Verified | Latest Update 2024

What is the speed of light? - Light can travel enormous distances under short periods of time. It is faster than any other phenomenon. It takes about 8 minutes for light to travel from the Sun to Earth. The speed of light in a vacuum is c=3x10^8 m/s. Why is light such an important tool for astronomers? - Because light is how we learn about distant objects without travelling there. It is also a measuring took of astronomy. Light is a wave and a particle. How are different kinds of light waves arranged in the EM spectrum? - Light is arranged on the electromagnetic (EM) spectrum from shortest wavelength (highest energy) to longest wavelength (lowest energy). The longer the wavelength the safer it is for people to be around. Gamma rays have the shortest wavelength and are used for cancer radiation. X-Rays are used for medical examinations. Infrared radiation is used in a TV remote, microwaves are used in microwave ovens, and the radio waves are used in mobile phones. They are arranged by frequency. What is the relationship between frequency, color, wavelength, and energy? - Color is how our eyes distinguish frequency. Speed of light equals frequency times wavelength. If frequency gets big then wavelength gets smaller and vice versa. E=hf means if energy gets larger so does frequency (because h is a constant). Frequency and wavelength are connected by speed of light. If you know one of c=f(lambda) then you are able to calculate them all.