Radiant Energy Overview

Radiant Energy Overview

• Radiant energy is energy transferred by electromagnetic waves and gravitational waves.
• It travels through a vacuum, unlike sound or water waves, which require a medium.
• Measured in joules (J).
• A mechanism for energy to enter or leave a system (e.g., campfire, clapping hands).
• Visible light is a form of electromagnetic radiation.
• There's a larger electromagnetic spectrum beyond visible light, including infrared.

How Radiant Energy Works

• Classical physics: Radiant energy as oscillating electric and magnetic fields perpendicular to each other and the direction of energy transfer.
• Quantum mechanics: Radiant energy in the form of photons, the smallest units of electromagnetic fields, with energy proportional to frequency (E=hf).
• Photons interact with matter at the atomic level. They can be absorbed, re-emitted, or reflected.
• Travels at approximately 300,000,000 meters per second in a vacuum
• Can be reflected and refracted

Electromagnetic Spectrum

• Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, ordered by increasing frequency.
• Each type with specific uses (e.g., radio waves for communication, X-rays for medical imaging).
• Part of the EM spectrum was discovered by William Herschel's experiments.

Measuring Radiant Energy

• Radiometry uses radiometers to quantify radiation flux (power) in watts or joules per second, which helps make images.
• Radiometry is essential for radio astronomy and remote sensing.

Radiant Energy Examples

• Gravitational radiation, from sources like neutron stars, also travels at approximately 300,000,000 meters per second.
• All energy on Earth originates from the sun, including nuclear energy from stars' fusion processes.

Uses of Radiant Energy

• Radio astronomy, optical astronomy, and telecommunications utilize radiant energy.
• Solar energy collectors capture solar radiation and convert it to chemical energy then electricity.
• Other technologies use radiant energy, including thermal heating lamps, light bulbs, and screens.
• Detecting and measuring Gravitational waves with LIGO and Virgo Interferometer. Measurements done using laser interferometry.

Collecting Radiant Energy

• The Sun is the primary radiant source for Earth.
• Nuclear fusion in stars produces radiant energy, converting hydrogen to helium. Stars eventually die, releasing elements into space.
• Earth's elements (formed by the accumulation of matter after supernovae) are then drawn into planets. The Sun's radiation drives weather and the water cycle.
• Life utilized radiant energy for survival and photosynthesis, then fossil fuels, as well as other radioactive materials provide sources.
• Radioactive elements decay, releasing radiant energy. This energy can be harnessed for electricity via nuclear power plants.