waves

Question 1

what is the relationship between the direction of energy transfer and vibration in a transverse wave ( wiggle) eg

Answer 1

the direction of vibration is perpendicular to the direction of energy transfer eg all waves in the electromagnetic spectrum, light waves and water waves

Question 2

what is the relationship between the direction of vibration and wave travel in a longitudinal wave (barcode)eg

Answer 2

direction of vibration is parallel to the direction of wave travel eg sound waves

Question 3

what is amplitude ?

Answer 3

amplitude is the vertical distance from the centre line to the top of a crest or the bottom of a trough (meters)

Question 4

what is wavelength?

Answer 4

Wavelength is the horizontal distance between the point on one crest and the identical point on the next wave often this is done as one crest to the next or one trough to the next

Question 5

what is frequency ?

Answer 5

frequency is the number of complete waves produced in 1 second or the number of waves passing a point in 1 second (Hz)

Question 6

what is period?

Answer 6

period is the time taken for one complete wave to be produced. (seconds)

Question 7

what does f=N/t mean?

Answer 7

frequency= number of waves ÷ time in seconds

Question 8

what does f=1/T mean

Answer 8

frequency = 1 ÷ period

Question 9

what does T=1÷ f mean

Answer 9

period = 1 ÷ frequency

Question 10

what is diffraction?

Answer 10

diffraction is the bending of waves around obstacles example - water waves passing through the gap Inna barrier

Question 11

what is the order of the electro magnetic spectrum in order of increasing frequency and decreasing wavelength

Answer 11

radio + TV, microwaves, infrared, visible light, ultra violet, x - rays, gamma rays

Question 12

which waves are the most dangerous

Answer 12

high frequency waves have high energy so x rays and gamma rays are the most dangerous

Question 13

what are the common properties of em spectrum waves

Answer 13

• they are all transverse waves
• they all travel at the speed of light (3x108)
• they all travel through a vacuum
• they all travel in straight lines

Question 14

what are the uses and detectors of radio + TV waves?

Answer 14

*used in telecommunications/ radio + TV/ broadcasting / RADAR
* detected by antennas or aerials
*Sources include stars, lightning, pulsars

Question 15

what are uses, detectors and sources for microwaves?

Answer 15

• used in microwave ovens and telecommunications
• detected by antenna and aerivals
• Sources include stars, cosmic microwave background radiation

Question 16

what are sources uses and detectors of infrared radiation

Answer 16

sources - any object that gives out heat
- detectors - ccd of thermal cameras or thermometers
uses - to treat muscle injuries, used in security systems

Question 17

what are the uses, sources and detectors of visible light

Answer 17

uses - lasers to cauterize wounds/ blood vessels, surgery, reading information from discs
detectors - the retina of the human eye
source - stars

Question 18

What are the uses, sources and detectors of UV light

Answer 18

Uses - treatment of rickets and skin conditions such as acne, hardening of gel nails/ fillings, security markings on bank notes/ passports
Detectors - florescent chemicals, photodiode Sources - the sun and other stars

Question 19

uses detectors and sources of x rays

Answer 19

uses include taking images on inside the body, sterilise medical instruments
- detected by photographic film
sources - stars

Question 20

uses, sources and detectors of gamma rays

Answer 20

Used in radiotherapy, sterilise medical instruments
detected by a Geiger Muller tube
Sources include the nuclei of unstable atoms ( radioactive decay)

Question 21

what is the law of reflection?

Answer 21

Angle of incidence = angle of reflection

Question 22

where is the signal strongest? - light

Answer 22

Place two antennas where reflected rays meet (focus)

Question 23

what is refraction?

Answer 23

Refraction is the change in speed of light as it travels from one medium to another medium of a different density.

Question 24

what happens during refraction when traveling into a denser medium?

Answer 24

*light waves slow down
* wavelength decreases
* light changes direction towards the normal of the incident ray was at an angle
* frequency remains unchanged
the opposite happens when light travels from a more dense medium into a less dense one

Question 25

what does a convex/ converging lense do and what kind of vision does it correct? (circle)

Answer 25

a convex lense brings parallel rays of light to a focus and corrects long sightedness

Question 26

what does a concave/ diverging lense do and what kind of vision does it correct?

Answer 26

A concave lense causes parallel rays of light to spread out and corrects short sightedness

Question 27

what is total internal reflection?

Answer 27

total internal reflection is the complete reflection of a light ray back into a dense medium when it hits the boundary between the dense medium and the less dense medium. No light escapes the medium.

Question 28

what are all of the formulas in this topic?

Answer 28

v=f x wavelength f= N÷t f= 1÷T t=1÷f d= VT

Question 29

what is the critical angle?

Answer 29

the critical angle is the angle of incidence that produces an angle of refraction at 90°

Question 30

if the angle of incidence is less than the critical angle what happens?

Answer 30

we get refraction as normal

Question 31

if the angle of incidence is equal to the critical angle what happens?

Answer 31

we get an angle of refraction of 90°

Question 32

if the angle of incidence is more than the critical angle what happens?

Answer 32

we get total internal reflection