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AS-Level Physics > Waves > Flashcards

Flashcards in Waves Deck (57)
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1

What is a wave?

A mechanism that allows energy to be moved from one place to another.

2

What is a transverse wave?

A wave which oscillates perpendicular to the direction of propagation and energy transfer.

3

What is a longitudinal wave?

A wave which oscillates parallel to the direction of propagation and energy transfer.

4

Give an example of a longitudinal wave.

Sound

5

What is the main difference between transverse and longitudinal waves?

Transverse waves can be polarised.

6

What is wavelength?

The distance between adjacent troughs.

7

What is frequency?

The number of waves passing a fixed point every second.

8

What is amplitude?

The distance between the centre line of the wave and the top of the crest.

9

What is the intensity of a wave?

-The energy deposited per second per metre squared.
-Power deposited per metre squared.

10

What is the intensity of a wave proportional to?

Amplitude squared

11

What is phase difference?

The fraction of one cycle between two vibrating points.

12

How can phase difference be expressed?

Wavelength or angle

13

What is the plane of polarisation?

The plane of oscillation of the particles that make up the wave.

14

What is the plane of polarisation for an EM wave?

The plane in which the electric field component vibrates.

15

What type of waves are slant polarised?

VHF (FM) radio waves

16

What is needed to form and stationary wave?

Two waves of the same type travelling towards each other that have the same frequency and amplitude.

17

What is an antinode?

The maximum displacement of the envelope.

18

What is a node?

Where the displacement of the envelope is zero.

19

What is a wavefront?

The line drawn along the crests of waves.

20

What is a ray?

A line drawn perpendicular to the wavefronts showing the direction of the wavefronts.

21

What two rules are always observed when reflecting at a plane mirror?

- angle of incidence = angle of reflection
-The incident and reflected ray are in the same plane.

22

What is the main use for mirrors reflecting light at 45°?

A periscope

23

What are the three properties of an image formed in a plane mirror?

-The image is virtual.
-The image is the same distance behind the mirror as the object is in front.
-The image is laterally inverted.

24

What is refraction?

The bending of a ray as it passes from one material into another and changes speed.

25

What is refraction?

The bending of a ray as it passes from one material into another and changes speed.

26

What is Snell's Law?

sini/sinr = 1n2 = velocity in material 1 / velocity in material 2 = n2/n1

27

What does 1n2 represent?

The relative refractive index from material 1 into material 2.

28

What does 1n2 also equal?

- 1 / 2n1
- velocity in material 1 / velocity in material 2

29

What is absolute refractive index?

The relative refractive index between a vacuum and the material.

30

What is the critical angle?

The angle of incidence for which the angle of refraction is 90°.