1. The Sun’s Energy

2. 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

3. 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.

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

5. 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

6. 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.

8. 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.

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

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

11. 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.

12. 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

13. 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)

14. 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.

15. 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.

16. 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.

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

18. 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

19. 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

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

22. 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