12. waves 2

Question 1

what is superposition

Answer 1

when waves meet, the resultant displacement = the vector sum of individual displacements

Question 2

what is phase difference

Answer 2

the difference in phase between two waves that arrive at the same point. (measured in pi)

Question 3

what must coherent waves have

Answer 3

1. same wavelength
2. same frequency

Question 4

what is the name of a wave with the same frequency, wavelength and a fixed phase difference.

Answer 4

a coherent wave

Question 5

if there is a phase difference of a multple of 2pi

Answer 5

the waves are IN-PHASE

Question 6

waves are out of phase when…

Answer 6

there is a phase difference of an odd multiple of pi, e.g pi, 3pi, 5pi

Question 7

what happens at a maxima point of two waves

Answer 7

constructive interference

Question 8

what happens at the point of destructive interference

Answer 8

minima

Question 9

what is path difference

Answer 9

the difference in distance travelled by two waves from their sources to the point where they meet

e.g a wave travelled 6 wavelengths, one travelled 4. Path difference = 2

Question 10

what did Young’s double slit experiment prove

Answer 10

the proof the nature of light is a wave

cannot be a particle at it has interference

Question 11

what is the equation used for the double slit experiment

Answer 11

λ=ax/D

λ=wavelength
a=slit space
x=fringe spaces (distance between maxima)
D= distance

Question 12

what is the limitation of the equation λ=ax/D

Answer 12

only works when D>a

Question 13

what is the difference between progressive waves and stationary waves CONSIDERING ENERGY TRANSFER

Answer 13

progressive waves have energy transferred in the direction of the wave

stationary waves have NO net energy transfer

Question 14

what is the difference between progressive waves and stationary waves CONSIDERING WAVELENGTH

Answer 14

progressive waves have a wavelength with a minimum distance between two adjactent points oscillating in phase **(between two peaks/ compressions) **

stationary waves have a wavelength TWICE the distance between adjacent nodes

Question 15

what is the phase difference of a progressive wave

Answer 15

the phase changes across one complete cycle of the wave

Question 16

phase difference for a stationary wave

Answer 16

all parts of the wave between 2 nodes are in phase. on different side of a node, they are in antiphase

Question 17

what is the difference between progressive waves and stationary waves CONSIDERING AMPLITIUDE

Answer 17

progressive wave: constant amplitude assuming no energy is lost to the surroundings

stationary wave: maximum amplitude at antinode - drops to zero at the node

Question 18

how many wavelengths for the first harmonic

Answer 18

0.5

Question 19

which harmonic has 1 whole wave length

Answer 19

2nd harmonic

Question 19

what is the fundamental frequency

Answer 19

minimum frequency of a stationary wave for a string

Question 20

constructive interference

Answer 20

The interference which occurs when two progressive waves arrive in phase at a point resulting in an amplitude which is the sum of the individual wave amplitudes

Question 21

destructive interference

Answer 21

when two progressive waves arrive in antiphase (180 degree phase difference) at a point producing an amplitude which is the difference between the amplitudes of the individual waves.

Question 22

antinode

standing wave

Answer 22

The point in a standing wave at which constructive interference occurs. The amplitude at this point is maximum.

Question 23

node

standing wave

Answer 23

The point in a standing wave at which destructive interference occurs. The amplitude at this point is zero.

Question 24

how to form a standing wave

Answer 24

set up two coherent counter-propogating progressive waves

Question 25

in a open ended tube, is it antinode/ node at the OPEN end?

Answer 25

antinode

Question 26

is the tube open ended or closed at a point where a node forms

Answer 26

closed

Question 27

which harmonics can occur in a DOUBLE ENDED OPEN tube

Answer 27

antinode at both openings: all values of f0

Question 28

which harmonics can occur in a tube with one end open

Answer 28

only odd harmonics can form (1st, 3rd 5th... harmonics)