6 end of the waves topic - lenses -->

Question 1

convex lenses

Answer 1

• shape of it bulges outwards
• light rays are speard out and then converge together and meet at the principle focus

Question 2

concave lenses

Answer 2

• the sides cave inwards in a wierd shape
• light rays start together at the principle focus and then spread out when going through the lense

Question 3

real image vs virtual image

Answer 3

REAL
- A real image is an image that can be projected onto a screen
- Rays of light actually pass through the image.
-
VIRTUAL
- cannot be projected onto a screen.
- It appears to come from behind the lens and can only be seen by looking through the lens.

Question 4

what is white and black light

Answer 4

white light - all the diff colours put together - reflect all wavelengths of visible light equally
black - the absence of colour - absorbs all wavelengths of visible light

Question 5

what is going on when something is OPAQUE

Answer 5

• either reflect or absorb all light that hits them.
• No light passes through.

Question 6

colour filters

Answer 6

• filter different wavelengths of light so only certain colours are transmitted and the rest are absorbed

Question 7

where is infrared radiation emitted from

Answer 7

the surface of an object

Question 8

whats the trend between the temperature of an object and how much infrared radiation it radiates

Answer 8

the hotter the object the more infrared radiation it radiates

Question 9

what happens when an object is HOTTER than its surroundings

Answer 9

hotter than surroundings = emits more IR than it absorbs and cools down

Question 10

what happens when an object is COLDER than its surroundings

Answer 10

cooler than surroundings = absorbs more IR than it emits and warms up

Question 11

results of the IR practcal - whats the best surface for IR

Answer 11

black matt

Question 12

what are black body objects

Answer 12

• absorb all radiation that hits it
• no radiation is reflected or transmitted
• these are the best possible emitters

Question 13

what happens on the black body radiation graph when the temperature increases

Answer 13

• temp increases = the intensity of every emitted wavelength increases
• the shorter the wavelength = the faster the intensity increases

Question 14

how does radiation effect the earth temperatures during day and night

Answer 14

DAYTIME
- earth absorbs the suns radiation - temperatures increase

NIGHTTIME
- less radiation is being absorbed than emitted - decrease in local temperature

Question 15

about sound waves

Answer 15

• caused by vibrating objects
• travels fastest in solids and slowest in gases
• ## when travelling through mediums the particles vibrate and therefore there is no sound in a vacuum bc no particles

Question 16

parts of your ear

Answer 16

1. ear drum
2. ossicles
3. semicircular canals
4. cochlea
5. auditory nerve - to the brain

Question 17

how do you hear sound - process

Answer 17

1. sound waves cause ear drum to vibrate
2. these are passed through the ossicles then through the semicircular canals an then into the cochlea
3. cochlea turns these vibrations into electricle signals when get sent to the brain

Question 18

whats the human hearing range

Answer 18

20 - 20,000 Hz

Question 19

what are ultrasound devices

Answer 19

• devices that produce electrical oscillations which convert to mechanical vibrations to produce sound waves above 20,000 Hz.

Question 20

ultrasound in medical imaging

Answer 20

1. ultrasound waves pass through the body and when they reach a boundary of different media some waves are reflected back and detected
2. this exact timing is processed by a computer to creates images of the foetus

Question 21

ultrasound in industrial imaging

Answer 21

1. used to find flaws in pipes or woods or metal etc
2. if there is a crack in these materials - the change in media will cause the waves to reflect sooner and therefore can be picked up by the ultrasound detector

Question 22

p waves

Answer 22

• type of seismic wave
• happens inside the earth
• longitudinal
• travel through solids and liquids
• faster than s waves

Question 23

s waves

Answer 23

• type of siesmic wave
• happens inside the earth
• transverse
• cant pass through liquids or gasses
• slower than p waves

Question 24

translucent

Answer 24

• transmit light but the rays are SCATTERED.
• We cannot see objects clearly through translucent objects.

Question 25

transparent

Answer 25

• transmit light WITHOUT scattering the rays.
• We can see objects on the other side of transparent objects.