waves pt2

Question 1

what type of wave is an electromagnetic wave

Answer 1

an electromagnetic wave is a transverse wave

Question 2

what do all electromagnetic waves have in common

Answer 2

all electromagnetic waves travel at the same velocity in air or in a vacuum

Question 3

describe the electromagnetic spectrum

Answer 3

the electromagnetic spectrum extends from low frequency, low energy waves to high frequency, high energy waves

Question 4

can human eyes detect electromagnetic waves

Answer 4

human eyes are only capable of detecting visible light

Question 5

what does the wavelength of an electromagnetic effect

Answer 5

the wavelength of an electromagnetic wave affects how it is absorbed, transmitted reflected, or refracted by different substances. this affects its uses.

Question 6

what does the direction of refraction depend on

Answer 6

the angle at which the wave hits the boundary

the material

Question 7

what’s it called when a material affects refraction

Answer 7

for light rays, the way in which a material effects refraction is called its refractive index

Question 8

describe how light travels from a material

Answer 8

from a material with a low refractive index to one with a higher refractive index, it refracts towards the normal

from a material with a high refractive index to one with a lower refractive index, it bends away from the normal

Question 9

why does refraction happen

Answer 9

refraction is due to the difference in the wave speed in the different media

Question 10

what happens when a light wave enters at an angle

Answer 10

when a light wave enters at an angle, a medium in which it travels slower

the first part of the light wave to enter the medium slows down.

the rest of the wave continues at higher speeds

this causes the wave to change direction, towards the normal

Question 11

how can waves be refracted?

Answer 11

when waves reach a boundary between one medium and another, they can be refracted

Question 12

what happens when constructing ray diagrams

Answer 12

rays must be drawn with a ruler

each straight section of ray should have a single arrow drawn on it to indicate the direction of movement

where the rays meets the boundary should be drawn at right angles to the boundary

all relevant angles should be labled

Question 13

why are ray diagrams used

Answer 13

ray diagrams are used whenever a diagram is needed to represent how light moves from one place to another

Question 14

name some examples of electromagnetic waves

Answer 14

radio waves 
microwaves 
infrared 
uv lights 
visible light 
x rays 
gamma rays

Question 15

what are radio waves used for and describe them

Answer 15

radio waves are used for televisions, radio, Bluetooth

radio waves are low energy waves and therefore, not harmful, making them ideal for radio transmission

Question 16

what are microwaves used for and describe them

Answer 16

microwaves are used for satellites, communications, cooking food

microwaves travel in straight lines through the atmosphere. this makes them ideal for transmitting signals to satellites in orbit and transmitting them back down to recievers

Question 17

what are infrared waves used for and describe them

Answer 17

infrared waves are used ofr electrical heaters, cooking food, infrared camares

Question 18

what is visible light used for and describe them

Answer 18

visible light waves are used for fiber optic communications

visible light travels down optic fibres from one end to the other without being lost through the sides

Question 19

what are ultraviolet waves used for and describe them

Answer 19

ultraviolet waves are used for energy effiecient light bulbs, security marking, sunbed

n energy-efficient light bulbs, UV waves are produced by the gas in the bulb when it is excited by the electrical current these UV waves are absorbed by the coating on the bulb, which fluoresces giving off visible light

Question 20

what are x rays used for and describe them

Answer 20

x rays are used for medical imaging and treatments

x rays are able to penetrate soft tissue but not bone a photographic plate behind a person will show a shadow of where the bones are

Question 21

what are gamma rays used for and describe them

Answer 21

gamma rays are used for sterilizing food, treatment of tumors

gamma rays are the most energetic of all electromagnetic waves and can be used to destroy bacteria and tumor

Question 22

what can radio signals be caused by

Answer 22

radio signals can be cause by oscillations in electrical circuits i.e an alternating current

Question 23

what is the frequency of the radio wave

Answer 23

the frequency of the radio wave produced matches the frequency of the electrical oscillation. this is how a radio signal is produced

Question 24

how is the signal received?

Answer 24

when radio waves are absorbed by a conductor they may create an alternating current with the same frequency as the radio wave. this is how the signal is received

Question 25

what happens when oscillation is induced

Answer 25

when oscillation is induced in an electrical circuit it creates an electrical signal that matches the wave

Question 26

how can EM waves be generated?

Answer 26

changes in atoms and the nuclei of atoms can result in EM waves being generated or absorbed over a wide frequency range

Question 27

what are the other ways waves can be generated?

Answer 27

electrons moving between energy levels as a result of heat or electrical excitation can generate waves

changes in the nucleus of an atom can generate waves i.e. an unstable nucleus can give out excess energy as gamma rays

Question 28

which waves are dangerous for the body

Answer 28

ultraviolet waves, x rays and gamma rays carry enough energy to have hazerdous effect on the human body

Question 29

what are those dangers?

Answer 29

ultraviolet waves can cause the skin to age prematurely and increase the risk of skin cancer