The Sun’s Energy

Essential Questions Illustrate that the sun’s energy arrives as radiation with a wide range of wavelengths, including infrared, visible, and ultraviolet, and that white light is made up of a spectrum of many different colors

REVIEW: What are waves? A wave is a disturbance that transfers energy from one place to another without transferring matter. A wave ONLY carries energy. It does not carry matter.

How waves transfer energy Energy is transferred through the collision of particles

Mechanical waves A mechanical wave is a wave that can only travel through matter A material in which a wave travels is called a medium

Transverse Waves A transverse wave is a wave in which the disturbance is perpendicular to the direction the wave travels Particles move up and down.

Crests and troughs The highest points on a transverse wave are crests The lowest points on a transverse wave are troughs Point of origin is the midpoint in a wave where amplitude begins. Amplitude reflects the amount of energy in a wave.

Wavelength Wavelength is the distance between a point on one wave and the identical point on the next wave.

Frequency Frequency is a measure of how many waves pass a point in a certain amount of time. Hertz are the units for frequency.

Longitudinal waves A longitudinal wave/compressional wave makes the particles in a medium move parallel to the direction that the wave travels Particles move back and forth.

Longitudinal waves Compressions are the regions of a longitudinal wave where the particles are closest together Rarefactions are the regions of a longitudinal wave where the particles are farthest apart

Example of mechanical waves Earthquakes! Produce sound waves, water waves, and seismic waves. Sound travels slowest through air and fastest through metals. Sound is caused by vibrations (the back and forth movement of matter)

Sound waves Remember sound is a form of energy. An echo is when a sound wave is reflected off a hard surface. A sound wave vibrates the ear drum.

Electromagnetic waves An electromagnetic wave is a wave that can travel through empty space AND through matter Radio waves, microwaves, infrared waves, and ultraviolet waves are examples. X-rays are used to show breaks in bones. Cellphones use microwaves.

Electromagnetic spectrum Gamma rays have the greatest amount of energy! Radio rays have the least amount of energy! Only a small part of the electromagnetic spectrum is visible.

Visible waves A form of electromagnetic waves that is visible to the human eye

Infrared Waves Infrared (IR) light is the part of the EM spectrum that people encounter most in everyday life, although much of it goes unnoticed. It is invisible to human eyes, but people can feel it as heat

Ultraviolet Waves Ultraviolet (UV) light has shorter wavelengths than visible light. Although UV waves are invisible to the human eye, some insects, such as bumblebees, can see them

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White light Combination of lights of different wavelengths in the electromagnetic spectrum

Electromagnetic waves from the sun The sun’s energy arrives as radiation with a range of wavelengths including infrared, visible, and ultraviolet. Infrared and visible light waves carry about 92% of the radiant energy that reaches Earth from the Sun Ultraviolet waves carry about 7%of the Sun’s energy

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