physics chapter 13

Question 1

what is the electromagnetic spectrum

Answer 1

the electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies of radiation in each region.

Question 2

what are the main regions of the continuous electromagnetic spectrum from longest to shortest wavelengths

Answer 2

• radiowaves
• microwaves
  -infrared
  -visible
• ultra violet
• x ray
• gamma rays

Question 3

how can we calculate the speed of light

Answer 3

speed of light = frequency x wavelength

Question 4

what are the properties that all electromagnetic haves share

Answer 4

• they are transverse
• can travel through a vacuum
• travel at the same speed in a vacuum
• form a continuous spectrum

Question 5

what is electromagnetic radiation

Answer 5

electromagnetic waves transfer energy as they move. the term radiation usually used to refer to the energy being transferred.

Question 6

what is the use of microwaves

Answer 6

• to cook
• radar system

Question 6

what is the use of visible light

Answer 6

• vision
• photosynthesis
• photography from camera

Question 6

what is the use of radiowaves

Answer 6

• tv and radio broadcasting
• telecommunication

Question 7

what is the use of infrared waves

Answer 7

• night vision
• remote control
• alarm system

Question 8

what is the use of gamma rays

Answer 8

• sterilising food
• treatment of cancer

Question 8

what is the use of ultraviolet

Answer 8

• to kill bacteria of microbes
• sterilising water

Question 9

what is the use of xrays

Answer 9

• kill cancer cells
• to take x ray picture
• detects flaws or cracks in a structure

Question 10

what is the danger of radiowaves

Answer 10

no known danger

Question 11

what is the danger of microwaves

Answer 11

internal heating of cells

Question 11

what is the danger of infrared waves

Answer 11

skin burns

Question 12

what are the harmful effects of excessive microwave exposure

Answer 12

• certain frequencies of microwaves are absorbed by water molecules
• humans contain lots of water so there is a risk of internal heating from the microwaves

Question 12

what is the danger of ultraviolet

Answer 12

damage surface cells and eyes lead to skin cancer and eye conditions

Question 12

what are the dangers of x ray and gamma rays

Answer 12

mutation or damage o cells in the body

Question 13

what are the harmful effects of excessive xray and gamma ray exposure

Answer 13

• penetrate the body and cause internal damage
• can cause the mutation of dna, causing cancer

Question 14

what are the harmful effects of excessive ultra violet exposure

Answer 14

• can kill cells and cause them to malfunction
• similar to visible light, except is invisible to the human eye and carries more energy

Question 15

how fast to electromagnetic waves travel

Answer 15

all electromagnetic waves travel at the same speed of 3x10^8 m/s in a vacuum

Question 16

how is wireless communication possible

Answer 16

the invisible radio waves and microwaves allow us to communicate wirelessly, there is no need to use a physical cable to link the transmitter and the receiver

Question 17

for what is low orbit satellites used for

Answer 17

• used for the monitoring of the weather, military applications and taking images of the earths surface

Question 18

for what is the geostationary satellites used for

Answer 18

used for telecommunication broadcasting around the world due to its high orbit

Question 19

what are the two type of signals

Answer 19

- analogue and digital

Question 20

describe the analogue signal

Answer 20

can take any value continuously

Question 21

describe the digital signal

Answer 21

can only take one of two states

Question 22

what are the benefits of digital signalling

Answer 22

- increases rate of data transmission - increased range due to accurate signal regeneration