Characteristics of Light

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Slide 1: 

Characteristics of Light

Slide 2: 

Electromagnetic Waves • waves that do NOT need a medium to travel

Slide 3: 

• transverse wave consisting of E & M fields at right angles Electromagnetic Waves

Slide 4: 

Electromagnetic Waves

E/M Spectrum : 

RADIO E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES INFRARED E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES INFRARED VISIBLE E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES INFRARED VISIBLE ULTRAVIOLET E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES INFRARED VISIBLE ULTRAVIOLET X - RAYS E/M Spectrum

E/M Spectrum : 

RADIO MICROWAVES INFRARED VISIBLE ULTRAVIOLET X - RAYS GAMMA E/M Spectrum

E/M Spectrum : 

RADIO TV/RADIO SIGNALS MICROWAVES RADAR and OVENS INFRARED PHOTOGRAPHY and P.T. VISIBLE LIGHT (RED - VIOLET) ULTRAVIOLET STERILIZATION X - RAYS MEDICAL GAMMA CANCER TREATMENTS E/M Spectrum

E/M Spectrum : 

RADIO  > 30 cm MICROWAVES INFRARED VISIBLE ULTRAVIOLET X - RAYS GAMMA 0.1 nm > > 10 -5 nm E/M Spectrum

E/M Spectrum : 

RADIO fHz MICROWAVES INFRARED VISIBLE ULTRAVIOLET X - RAYS GAMMA f < 10 22 Hz E/M Spectrum

E/M Spectrum : 

RADIO energy MICROWAVES INFRARED VISIBLE ULTRAVIOLET X - RAYS GAMMA E/M Spectrum increases

Slide 16: 

E / M Spectrum

E/M Spectrum : 

E/M Spectrum What humans see is part of the VISIBLE SPECTRUM

Slide 18: 

~ 700 nm ~ 400 nm

Slide 19: 

All E / M waves travel at the speed of light. c = 3.00 x 10 8 m/s E/M Spectrum

Slide 20: 

…which changes the formula to c = f E/M Spectrum

Example Problem : 

Example Problem The AM radio band extends from 5.4 x 105 Hz to 1.7 x 106 Hz. What are the longest and shortest wavelengths in this frequency range?

Slide 22: 

We will consider light to travel as RAYS from the wave fronts. E/M Spectrum

Slide 23: 

Is it easier to see with a 100 W bulb or a 25 W bulb? Is it easier to see closer to a light or farther away from a light?

Slide 24: 

This suggests that the intensity of light depends on both the amount of light energy emitted from a source and the distance from the light source.

Intensity of Light : 

Intensity of Light Just like sound waves, light has intensity. I = Power / 4pr 2

Intensity of Light : 

Intensity of Light Brightness decreases by the square of the distance from the source. I = Power / 4pr 2

Slide 27: 

Galileo performed an experiment to measure the speed of light by timing how long it took light to travel from a lamp he was holding to an assistant about 1.5 km away and back again. How long did it take for the light to travel this distance?

Slide 28: 

How bright would the sun appear to an observer on Earth if the sun was four times farther from Earth than it actually is?

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