P1 - Waves

Question 1

List the EM wavesfrom longest to shortestwave length.

Answer 1

radio, micro, IR, visible, UV,X-Ray, gamma

Question 2

State one differencebetween UV and visible light.

Answer 2

UV has a higher frequency,shorter wavelength, has moreenergy

Question 3

What does redshift tellscientists about galaxies?

Answer 3

that they are moving awayfrom Earth

Question 4

Why is the redshift notthe same for all galaxies?

Answer 4

galaxies are moving awayfrom Earth at differentspeeds

Question 5

What does redshiftsuggest about the Universe?

Answer 5

that it is expanding

Question 6

What happens when ametal aerial absorbs radiowaves?

Answer 6

it creates an alternatingcurrent with the samefrequency as the radio wave

Question 7

Why would an X-raytelescope placed on Earth notbe able to detect X-raysemitted from distance stars?

Answer 7

X-rays cannot penetrate theatmosphere

Question 8

Give an example of IRbeing used forcommunication.

Answer 8

TV, remote controls, opticalfibres, remote control,thermal imaging

Question 9

Give the differencebetween transverse andlongitudinal waves.

Answer 9

oscillations areperpendicular to the directionof energy transferred fortransverse waves but parallelfor longitudinal waves

Question 10

Why can you hear butnot see the TV in anotherroom?

Answer 10

light waves will notdiffract but sound waves willbecause the width of thedoor is similar to thewavelength of the soundwave.

Question 11

Why do thermalimaging cameras work betterat night than during the day?

Answer 11

at night the surroundingsare cooler so they emit lessIR than a person; thedifference in IR emitted islarger

Question 12

Give two properties ofall EM waves.

Answer 12

Travel at the same speed,transfer energy, travel througha vacuum, can be reflected,refracted, diffracted, absorbed,are transverse, travel in straightlines

Question 13

What is the propertyof microwaves that allowsthem to be used for satellitecommunications?

Answer 13

They can pass through theionosphere.

Question 14

An image in the mirroris virtual. Why?

Answer 14

Image is formed byimaginary rays crossing;formed behind the mirror

Question 15

if microwaves areabsorbed by a tennis ball,what effect do themicrowaves have on the ball?

Answer 15

Make it hotter

Question 16

How does red shiftprovide evidence for the BigBang theory?

Answer 16

Redshift of distant galaxies isgreater which means that thefurther apart galaxies are thefaster they are moving awayfrom each other; relationship isproportional, so must havestarted at same point.

Question 17

Compare a quiet andlow pitch sound to a loud andhigh pitch sound.

Answer 17

Low pitch has longerwavelength and lowerfrequency/ Quieter sound haslower amplitude

Question 18

What is cosmicbackground radiation?

Answer 18

Microwave noise thatreaches Earth from manystars and galaxies; radiationcreated just after the BigBang

Question 19

How do you calculatewave speed?

Answer 19

wave speed (m/s) =frequency (Hz) x wavelength(m)

Question 20

Describe the Big Bangtheory.

Answer 20

Universe started in oneplace; huge explosion tookplace and sent matteroutwards; Universe has beenexpanding ever since.

Question 21

What is the Universe?

Answer 21

innumerable collectionof galaxies

Question 22

What is redshift?

Answer 22

light moves towards thered end of the spectrum

Question 23

Describe how thesound changes when a cardrives past you.

Answer 23

car drives towards you:wavelength shortens andfrequency increasesCar drives away from you:wavelength lengthens andfrequency decreases

Question 24

Why do scientists useX-ray, gamma ray andmicrowave telescopes toobserve the Universe?

Answer 24

stars emit different typesof EM radiation

Question 25

How is the wavelengthof CMBR likely to changeover the next billion years?

Answer 25

increase as Universecontinues to expand

Question 26

What is the Dopplereffect?

Answer 26

change in wavelength andfrequency when the source ofwaves or observer moves( relative to each other)

Question 27

Give one example ofmicrowaves being used forcommunications.

Answer 27

Mobile phone/satellitecommunications

Question 28

What are the dangersof IR, UV and micro waveradiation?

Answer 28

IR- skin burnsUV- skin burns, skin cancerMicrowaves- burns, cancer

Question 29

Give a use of radiowaves.

Answer 29

TV broadcasting, mobilephone communications

Question 30

Describe an imageformed in the mirror.

Answer 30

virtual and upright, samedistance behind the mirror asobject is in front of themirror

Question 31

What is refraction?

Answer 31

when light travels fromone medium to another, itchanges direction because it’sspeed has changed; this isdue to the density of themedium having changed

Question 32

What are sound wavescaused by?

Answer 32

vibrations

Question 33

How can you reducethe amount of noisetransmitted through walls?Why does the method work?

Answer 33

panel the walls with woodor plaster or similar so thesound is reflected back orabsorbed

Question 34

What is diffraction?

Answer 34

the spreading of waves whenthey pass through a gap oraround the edges of an obstaclewhich has a similar size as thewavelength of the wave

Question 35

How do microwavesheat food?

Answer 35

microwaves are absorbedby the water inside the food,the water heats the food

Question 36

What does the termfrequency mean?

Answer 36

number of waves persecond

Question 37

What do the wordscompression and rarefactionmean?

Answer 37

compression is squeezingtogether, rarefaction isstretching apart

Question 38

What is the law ofreflection?

Answer 38

angle of incidence = angleof reflection

Question 39

What are the twomain pieces of evidence forthe Big Bang theory?

Answer 39

Redshift and cosmicmicrowave backgroundradiation