Unit 3 - waves part 1 (basics and EM spectrum) Flashcards

Question

How does medium affect the speed of sound?

Answer 1

- as density of medium increases, so does speed of sound - sound travels fastest in a solid where the particles are closest together (as solids are densest SoM) and they can transfer vibrations faster between particles (as sound is wave where medium oscillates parallel to direction of wave travel) - in gas + liquids, particles are further away (less dense) so vibrations take longer to pass between particles

Answer 2

20-20,000Hz

Answer 3

- prenatal ultrasound scans - crack detection in machinery - breaking kidney stones

Answer 4

- probe emits + receives the waves - ultrasound transmits through the tissue - the waves are reflected whenever there is a change in density - the time taken to recieve echo x speed of sound = depth of fetus, and this is done repeatedly to form an image on the screen

Answer 5

- the transceiver transmits ultrasound through the metal - waves are reflected back to transceiver when the crack is detected to see how deep in the crack is - time taken and speed through medium is multiplied to find how deep the crack is

Answer 6

- radio waves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays (Remember Red Monkey Is Viewed Under Xavier Gabriel)

Answer 7

- all are transverse - all travel at 3 x 10^8m/s in a vacuum - all can be reflected, refracted and diffracted

Answer 8

- radio + TV broadcasting over long distance - long wavelength means radio waves from transceivers can be reflected by ionosphere to other transceivers around the world to broadcast information - they can diffract around obstacles like hills

Answer 9

- cooking food with large water content + mobile & satellite communication - water molecules in food absorb large amounts of kinetic energy from microwaves so food particles vibrate faster, heats and cooks - they are able to penetrate though atmosphere to satellites and can carry more information than radiowaves (due to shorter wavelength)

Answer 10

- cooking (grills/toasters): hot objects emit IR which is absorbed by food, increasing its kinetic energy and heating/cooking it - short-range communication (tv remotes): IR travel short distances and do not easily pass through walls, making them ideal for controlling specific devices in a room without interference - security cameras (night vision): cameras detect IR emitted by warm objects (like people) or use IR LEDs to illuminate an area; IR is absorbed and reflected quickly, allowing for clear images in total darkness

Answer 11

- traffic systems, glasses/ contacts, fibre optic cables - coloured light transmits through the air and is absorbed by eyes - refraction of light through curved glass is absorbed by eyes to correct vision - light reflected in cables to travel long distances

Answer 12

- security tagging banknotes, sterilising, tanning - fluorescent ink absorbs UV and reflects white light into eyes to be absorbed, discreetly tagging banknotes - bacteria absorbs UV and is killed, sterilising surgical equipment - suncream absorbs and/or reflects UV instead of it being absorbed by skin

Answer 13

- airport security scanners, scanning of skeleton - waves are transmitted through bags and picked up by a transceiver to form an image of contents to check for unauthorised items - transmitted through body tissue but reflected by bones so the film has a shadow of the bones to identify cracks

Answer 14

- radiotherapy cancer treatment, medical tracer - high energy waves are directed to the cancer cells which absorbs them and the cells die - patient is injected w radioactive tracer which absorbs gamma so blockages can be seen during a scan

Answer 15

UV, X-rays and gamma rays

Answer 16

have the highest frequency = highest energy which means that they’re more dangerous

Answer 17

- overexposure of ionising radiation causes atoms in cells to lose electrons, ionising them - this can mutate DNA and cause cells to rapidly divide, leading to cancer

Answer 18

harms the eyes by damaging the retinas, potentially causing blindness if extreme

Answer 19

Burns the skin and tissue

Answer 20

- the apparent shift in wavelength and frequency of a wave emitted by source moving relative to an observer - as wavelength decreases, frequency increases - the faster the source is moving relative to the observer, the more pronounced the difference is in pitch and volume

Answer 21

- can be observed whenever sources of waves move - frequency of the sound waves emitted by ambulance or police sirens goes from a high pitch (high frequency) to a low pitch (low frequency) as the vehicle whizzes past - galaxies in outer space emit light waves which appear redder (longer wavelength) to an observer on Earth because the stars are moving away from (and would appear bluer w/shorter wavelength if they were moving towards us)

Answer 22

To an observer standing in front of an object moving towards them: - wavefronts appear to compress so the wavelength appears to decrease and the frequency appears to increase = higher pitch To an observer standing behind an object moving away from them: - wavefronts appear to stretch so wavelength appears to increase and frequency appears to decrease = lower pitch

Unit 3 - waves part 1 (basics and EM spectrum) Flashcards

(46 cards)