Light is responsible for photosynthesis and indirectly produces oxygen. It heats the ocean, air and land, initiating weather patterns and partly causing ocean currents and the water cycle. Light displays properties of waves as it reflects, diffracts, and refracts. It is an electromagnetic wave that propagates without a medium and has a velocity, wavelength, and frequency. The electromagnetic spectrum includes invisible forms of light like gamma rays and radio waves. In the visible spectrum, color is the reflected light wavelength, while white light is a combination of all visible wavelengths.

1. Light
Characteristics, velocity, frequency,
wavelength, The Electromagnetic
Spectrum, Colors

2. Light
Significance of Light
 Responsible for photosynthesis
 Indirectly responsible for production of
Oxygen
tesCarbohydraOCOOH  222
Sunlight

3. • Heats up ocean, air, and land which initiates
different weather patterns
• Partly responsible for ocean currents
• Partly responsible for evaporation and
condensation of rain.

4. Light is a Wave
Light is a wave because it displays some
properties of mechanical waves.
 It reflects. (Reflection)
 It diffracts. (Diffraction)
 It refracts. (Refraction.

5. Light as Electromagnetic Wave
• Light can propagate without the existence of
physical medium (solid, liquid, gas)
• Light has velocity, wave length, and frequency.
• Light is made up of “Many Light Waves”.
Invisible Light
Invisible Light
Gamma Rays
X-Rays
Ultraviolet rays
Infrared rays
Microwaves
Radio waves
High Frequency,
short wave length
Low Frequency, Long
wavelength

6. Electromagnetic Spectrum

7. Each light wave in the electromagnetic spectrum
carries different Frequency and Wave Length,
but their VELOCIY is the SAME.
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frequencyf
lengthwave
velocity
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8. Color
Visible Light (light with colors) – represent a
band of light waves whose wavelength is
between 380 nm – 739 nm.
Monochromatic light – a light wave of one
wavelength
Colors – The light ray which is reflected.

9. White Light is the combination of all visible light.
White – is not a color.
Black – is also not a color. (No visible light is
reflected.
Different organisms are sensitive to different wave
lengths.
Snakes, and crocodiles – can see the red to infrared
color

10. Humans, and primates are sensitive to green
colors
Bats – sensitive to infrared light

11. Human Eye
Retina – inside surface of the pupil. Collections
of cells which are responsible for light
detection.
Rods – Sensitive to the intensity of light
Cones – Sensitive to the wavelengths of visible
light.

12. Cone Sensitivity Curve
Why are primates (humans, monkeys, apes)
sensitive to green?

13. Colors – the color we see is the reflected light of
ROYGBIV

14. Properties of Objects in Relation to Light
Transparent – light passes straight through the
object
Translucent – some light passes through, some
are reflected, some are refracted (scattered
into many directions)
Opaque – no light passes through the object.