EMR

Question 1

EMR

Answer 1

Defined as a wave with a changing electric and magnetic field perpendicular to each other
- EMR is all the energy from sun, can also move through empty space

Question 2

Ionizing radiation

Answer 2

Has enough energy to break chemical binds and remove the electrons (UV to gamma)

Question 3

Non-ionizing radiation

Answer 3

Does not have enough energy to break chemical bonds but can heat up (radio waves to visible light)

Question 4

Universal wave equation

Answer 4

Applies to all types of waves- speed is always the speed of light (c = 3.00 x 10^8 m/s )

Question 5

The electromagnetic spectrum

Answer 5

• the complete range of EMR; arranged using wavelength and frequency

Question 6

Energy content of EMR

Answer 6

1. Frequency - higher frequency means more energy
2. Intensity - “brightness”- more waves means more energy

Question 7

Radio waves and TV waves

Answer 7

• lowest frequency
• longest wavelength
• lowest energy
• source: vibrating electrons in circuits; used for communications
• penetrates atmospheric gases and most building materials
• can not penetrate metal so antennas are required
• elf waves extremely low frequency
• radio waves are used for MRI’s
• do not harm body tissue
• low energy

Question 8

Microwaves

Answer 8

• used for radar (higher f ), satellites, and cooking food (lower f ). They react with water molecules
• source: high frequency vibrations of electrons in specialized electronic circuits
• used in communications because can penetrate through snow, haze, smoke, glass and plastic
• can not penetrate metal
• electrons accelerated in vacuum tubes
• Transmit more energy than radio waves

Question 9

Infrared radiation

Answer 9

• used in remotes for tvs
• source: vibrations of molecules in warm and hot objects creating heat
• any object that is warm or hot emits infrared radiation
• skin sensors can detect IR using heat receptors, energy is not seen, it is felt
• used for cooking and detection of objects in low light conditions
• cell damage due to overheating
• can burn living tissues
• can penetrate atmospheric gases from a remote control to a TV

Question 10

Visible light

Answer 10

• complete range of all colours that can be seen by the eye and enable photosynthesis
• visible light is emitted by things that are hot
• electrons are jumping to other molecules
• light is not a wave, but a photon, the higher frequency means more energy
• can penetrate through the atmosphere and the lens of the human eye

Question 11

Photosynthesis

Answer 11

• plants use visible light photons and absorb the energy of red and violet light to grow
• photons of green light are not absorbed so the energy is reflected and we see the green colour reflected by the plant

Question 12

Ultraviolet light

Answer 12

• emitted by very hot objects
• Photons have more energy than visible light, this can cause skin cancer
• ionizing radiation
• includes serialization of food products and safety glasses
• divides into 3 types-
  -UVA/B can penetrate the ozone layer, high energy
• UVB- causes skin to tan
• UVC- absorbed by ozone layer, causes DNA mutations that can lead to death

Question 13

X- rays

Answer 13

• high energy waves f = 10^21
• created when high speed electrons strike metal and decelerate, produced using a high voltage tube
• penetrates skin easily, are absorbed into bones
• powerful form of ionizing radiation, cause cancer DNA mutations and death of cells
• can cause cancer of the bone and skin
• can penetrate soft body tissues like blood cells

Question 14

Gamma radiation

Answer 14

• highest energy radiation, shortest wavelength and highest frequency
• are radioactive photons from fission and fusion reactions
• are ionizing radiation; cause DNA mutations very quickly causing cancer and death of cells
• also used to treat cancer
• can penetrate thin sheets of metal