13 - superposition of waves

Question 1

sinusoidal

Answer 1

having the form of a sin wave

Question 2

principle of superposition

Answer 2

when two or more waves meet at a point, the resultant displacement is the sum of the displacements of the individual waves

Question 3

diffraction

Answer 3

the spreading of a wave when it passes through a gap or past the edge of an object

Question 4

gap width > wavelength

Answer 4

hardly noticible diffraction

Question 5

gap width = wavelength

Answer 5

diffraction effect greatest

Question 6

gap width < wavelength

Answer 6

limited diffraction

Question 7

radio waves easily diffracted outside?

Answer 7

yes

Question 8

microwaves easily diffracted outside?

Answer 8

no

Question 9

interference

Answer 9

the formation of points of cancellation and reinforcement where two coherent waves pass through each other or the superposition of two or more waves from coherent sources

Question 10

antiphase

Answer 10

phase difference = 180°

Question 11

constructive interference

Answer 11

when two waves reinforce to give increased amplitude at a point in space

path diff = n*wavelength

Question 12

destructive interference

Answer 12

when two waves cancel to give reduced (or zero) amplitude at aq point in space

path diff = (n+0.5) *wavelength

Question 13

coherent sources

Answer 13

two sources with exactly same frequency and have zero constant phase difference

Question 14

path difference

Answer 14

the extra distance travelled by one of the waves compared with the other, often given in terms of the wavelength of the waves

Question 15

interference maxima

Answer 15

regions where light waves from two slits arrive in phase with each other (constructive interference) aha fringes

the bright areas

Question 16

coherence

Answer 16

term used to describe two waves emitted from two sources that have constant phase difference

sources emitting this are called coherent sources

Question 17

waves can only have constant phase difference if

Answer 17

the frequency is same and remains constant

Question 18

Young double slit experiment

Answer 18

. two sets of waves from coherent sources (single laser beam through two slits)
. interference occurs where two diffraced beams overlap
. Will get interference fringes on screen

calculate slit seperation, fringe seperation, slit to screen distamce

Question 19

double slit equation

Answer 19

wavelength = ax/D

a = distance between slit centers
x = distance between adjacent dark/bright fringes
D = distance from slit midpoints to central fringe on screen

Question 20

transmission diffraction grating

Answer 20

. many slits slide
. lines to diffact

Question 21

reflection diffraction grating

Answer 21

. lines made on a reflecting surface
. light is both diffracted and reflected

Question 22

bright fringes

Answer 22

maxima

Question 23

middle fringe of transmission grating is called

Answer 23

zeroth order maxima
n =0

Question 24

wavelength from diffraction grating formula

Answer 24

dsin theta = n *wavelength

d = seperation between adjacent line of grating
theta = angle for nth order maximum
wavelength = wavelength of monochromatic light incident normally at the diffraction grating
n = order of maximum, has integer values

Question 25

dispersion

Answer 25

the splitting of light into it’s component wavelengths

Question 26

is diffraction grating better than double slit

Answer 26

yes

. more precise
. more distance
. easier angles