Electromagnetic Spectrum

1. Electromagnetic Spectrum CH 27-Physics (B) Fall, 2010

2. Electromagnetic Waves • Electric and magnetic fields always exist ……………………. • When ever one is ………………. the other is ……………………. • The fields can exist in a …………………... • They are at …….o to each other. • The electromagnetic wave move at ……..o to the fields. The ……………… of the wave refers to the number of ……………………………

3. Electromagnetic Waves • Electric and magnetic fields always exist together. • When ever one collapses the other is generated. • The fields can exist in a vacuum. • They are at 90o to each other. The frequency of the wave refers to the number of cycles per second

4. Electromagnetic Spectrum • All the different types of electromagnetic waves form the ………………………………………………. • Changing the ………………………. changes the properties of the waves.

5. Electromagnetic Spectrum • All the different types of electromagnetic waves form the Electromagnetic Spectrum. • Changing the frequency changes the properties of the waves.

6. Radio Waves • Radio waves have the ………………… wavelengths in the electromagnetic spectrum. • These waves can be longer than a ………………. or as short as a ……………. • Radio waves do more than just bring music to your radio. • They also carry …………. for your ……………… and ………………….. phones

7. Radio Waves • Radio waves have the longest wavelengths in the electromagnetic spectrum. • These waves can be longer than a football field or as short as a football. • Radio waves do more than just bring music to your radio. • They also carry signals for your television and cellular phones

8. Microwaves • Microwaves have wavelengths that can be measured in ……………………………! • The longer microwaves, those closer to a ………….. in length, are the waves which heat our food in a ………………… oven. • Microwaves are good for ……………… ………………… from one place to another because microwave energy can ……………………. haze, light rain and snow, clouds, and smoke.

9. Microwaves • Microwaves have wavelengths that can be measured in centimeters! • The longer microwaves, those closer to a foot (~30 cm) in length, are the waves which heat our food in a microwave oven. • Microwaves are good for transmitting because microwave energy can penetrate through haze, light rain and snow, clouds, and smoke.

10. Infrared Radiation • The ………………… that we feel from sunlight or a fire is infrared radiation. • ………………., near infrared waves are not hot at all - in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV's ……………. …………….. • To make infrared pictures like the one above, we can use special cameras. The …………….. areas are the warmest and the …………………….. areas are the coldest.

11. Infrared Radiation • The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared. • Shorter, near infrared waves are not hot at all - in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV's remote control. • To make infrared pictures like the one above, we can use special cameras. The orange areas are the warmest and the white-blue areas are the coldest.

12. Visible Light • Visible light is made up of the various ..................... of colored light. • The ……… is determined by the frequency of the light. • When electromagnetic radiation of this frequency falls on our ……………. our brain interprets it as colour.

13. Visible Light • Visible light is made up of the various frequencies of colored light. • The colour is determined by the frequency of the light. • When electromagnetic radiation of this frequency falls on our retina our brain interprets it as colour.

14. Ultraviolet (UV) light • Ultraviolet (UV) light has ………… wavelengths than visible light. • Ultraviolet radiation seems to play an important role in ……… some animals have colours that change in UV light – other animals can detect UV light. • Though these waves are invisible to the human eye, some insects, like …………….., can see them! • Also used for ................... …………….

15. Ultraviolet (UV) light • Ultraviolet (UV) light has shorter wavelengths than visible light. • Ultraviolet radiation seems to play an important role in nature some animals have colours that change in UV light – other animals can detect UV light. • Though these waves are invisible to the human eye, some insects, like bumblebees, can see them! • Also used for security coding.

16. X - Rays • X-Ray radiation has a high …………………….. ability and can pass right through our bodies. • X-rays film forms images depending on the ………………….. of the X-rays falling on it. • The ……………….. left by things that the X-rays can't travel through (like bones or metal) form the …………… on medical X-rays. • Over exposure can cause ……….. …………………….

17. X - Rays • X-Ray radiation has a high penetration ability and can pass right through our bodies. • X-rays film forms images depending on the intensity of the X-rays falling on it. • The shadows left by things that the X-rays can't travel through (like bones or metal) form the images on medical X-rays. • Over exposure can cause tissue damage.

18. Gamma-rays • Gamma-rays have the …………………… wavelengths and the most energy of any other wave in the electromagnetic spectrum. • These waves are generated by …………………………. and in nuclear explosions. • Gamma-rays can …………. living cells, a fact which medicine uses to its advantage, using gamma-rays to kill …………… cells.

19. Gamma-rays • Gamma-rays have the smallest wavelengths and the most energy of any other wave in the electromagnetic spectrum. • These waves are generated by radioactive atoms and in nuclear explosions. • Gamma-rays can kill living cells, a fact which medicine uses to its advantage, using gamma-rays to kill cancerous cells.