4.1- WAVES AND VIBRATIONS

Question 1

What are waves that pass through a substance?

Answer 1

vibrations which pass through that substance

Question 2

How are sound waves in air created?

Answer 2

by making surface vibrate so it sends compression waves through the surrounding air

Question 3

Examples of waves that pass through a substance (3)

Answer 3

sound waves
seismic waves
waves on strings

Question 4

What are sound waves, seismic waves and waves on strings referred to as?

Answer 4

mechanical waves

Question 5

What are mechanical waves?

Answer 5

when waves progress through a substance, particles of substance vibrate in certain way which makes nearby particles vibrate in same way, and so on

Question 6

What are electromagnetic waves?

Answer 6

oscillating electric and magnetic fields that progress through space without need for a substance

Question 7

What does the vibrating electric field of an EM wave generate?

Answer 7

a vibrating magnetic field

Question 8

What does the vibrating magnetic field of an EM wave generate?

Answer 8

a vibrating electric field

Question 9

What are the EM waves

Answer 9

radio waves 
microwaves 
infrared radiation 
visible light 
UV radiation 
X-rays 
gamma radiation

Question 10

What are longitudinal waves?

Answer 10

waves in which the direction of vibration of particles is parallel to direction in which wave travels

Question 11

Examples of longitudinal waves? (3)

Answer 11

sound waves

primary seismic waves compression waves

Question 12

What happens when one side of a slinky is moved to and fro repeatedly?

Answer 12

each “forward” movement causes a compression wave to pass along the slinky as the coils push into each other

Question 13

What does the “reverse” movement on a slinky cause it to do?

Answer 13

causes the coil to move apart so rarefaction wave passes along the slinky

Question 14

What are transverse waves?

Answer 14

waves in which the direction of vibration perpendicular to the direction in which wave travels

Question 15

Examples of transverse waves? (3)

Answer 15

EM waves
secondary seismic waves
waves on a string or wire

Question 16

What happens when one end of a rope is moved from side to side repeatedly?

Answer 16

sideways movements travel along rope, as each unaffected part of rope pulled sideways when part next to it moves sideways

Question 17

When are transverse waves plane-polarised?

Answer 17

vibrations stay in one plane only

Question 18

If vibrations change from one plane to another, what are the transverse wave described as?

Answer 18

unpolarised

Question 19

What waves cannot be polarised?

Answer 19

longitudinal waves

Question 20

Example of sources of unpolarised waves (2)

Answer 20

light from filament lamp or a candle

Question 21

What happens if unpolarised light is passed through a polaroid filter?

Answer 21

transmitted light polarised as filter only allows through light which vibrates in certain direction, according to alignment of its molecules

Question 22

What happens if unpolarised light is passed through two polarised filters?

Answer 22

transmitted light intensity changes if one polaroid turned relative to other one

Question 23

What is the filters said to be when the transmitted intensity is a minimum? (polarisation)

Answer 23

crossed

Question 24

When the filters are polarised can the polarised light from the first filter pass through the second filter?

Answer 24

no

Question 25

Why can the polarised light not be able to pass through the second filter when the filters are crossed?

Answer 25

alignment of molecules in second filter is at 90° to alignment in first filter

Question 26

What is light apart of?

Answer 26

spectrum of EM waves

Question 27

What is the plane of polarisation of an EM wave defined as?

Answer 27

plane in which electric field oscillates

Question 28

What do polaroid sunglasses do?

Answer 28

reduce glare of light reflected by water/ glass

Question 29

How do polarised sunglasses work?

Answer 29

reflected light polarised + intensity reduced when it passes through polaroid sunglasses