Physics

1. Electormagnetic Spectrum
Dr. Jayasudha S, Asst. Professor, NSS College, Cherthala
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2. What is the Electromagnetic Spectrum?
•The electromagnetic spectrum is the complete
spectrum (or continuum) of all forms of “light”
•An electromagnetic wave consists of electric
and magnetic fields which vibrate -thus making
waves.
Dr. Jayasudha S, Asst. Professor, NSS
College, Cherthala
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3. EM Spectrum
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4. The electromagnetic spectrum consists of:
•radio waves
•cell phone waves
•microwaves
•radar waves
•infrared waves
•visible light waves
•ultraviolet waves
•x-ray waves
•gamma waves
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6. Waves
•Properties of electromagnetic waves include
speed, frequency and wavelength
•Speed (s), frequency (f) and wavelength (l) are
related in the formula:
•s= fxl
•All light waves travel at a speed of 3 x108m/s in a
vacuum
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7. Wavelength, Frequency, Energy
•Electromagnetic wave characteristics:
–short wavelengths have a high frequency
–long wavelengths have a low frequency
•Electromagnetic waves & Energy:
–high frequency waves have high energy
–low frequency waves have low energy
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9. Radio waves
•Low energy waves with longest wavelengths
•Includes FM, AM, radar and TV waves
•Wavelengths of 1 m (10 -1 m) and longer
•Low frequency
•Used in many devices such as remote control items, cell phones,
wireless devices, etc.
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10. Microwaves
Only radio waves are longer
Wavelength 1 x 10-1m to 1 x 10 -4m (1 m to 0.001 m)
used for communication, medicine and consumer use
(microwave ovens)
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11. Infrared waves
•Invisible electromagnetic waves that are detected as heat
•Can be detected with special devices such as night goggles
•Used in heat lamps
•Higher energy than microwaves but lower than visible light
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12. Visible Light
•The portion of the electromagnetic spectrum that human eyes can
detect
•ROY G BIV (red, orange, yellow, green, blue, indigo, violet)
•Which color has the lowest frequency?
•red has the lowest frequency –violet the highest
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13. Ultraviolet waves
•Higher energy than light waves
•Can cause skin cancer and blindness in humans
•Used in tanning beds and sterilizing equipment
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14. X-Rays
•High energy waves
•Used in medicine, industry and
astronomy
•Can cause cancer
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15. Gamma rays
•Highest energy
•Blocked from Earth’s surface by atmosphere
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16. Exercises
1. What is the relationship between frequency and wavelength?
2. What characteristic of gamma waves gives them their high energy?
3. What does ROY G BIV mean? What part of the electromagnetic spectrum
does it refer to?
4. Which color is more energetic, red or yellow?
5. Which type of wave travels faster, gamma or radio?
6.. Why are microwaves more dangerous than radio waves?
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17. Thank You
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