A-LEVEL PHYSICS: 3.4.1: Single Slit Diffraction (SaveMyExams)

Question 1

diffraction:

Answer 1

the spreading out of waves after they pass through a narrow gap or around an obstruction

Question 2

what does the extend of wave diffraction depend on?

Answer 2

the width of the aperture compared to the wavelength

Question 3

when aperture is much smaller than the wavelength of the wave:

Answer 3

no diffraction

Question 4

when aperture is much bigger than the wavelength of the wave:

Answer 4

no diffraction

Question 5

when the aperture and the wavelength of the wave are similar size:

Answer 5

diffraction occurs

Question 6

when the wavelength is bigger than the aperture:
explain:

Answer 6

more diffraction occurs

wave spreads out more

Question 7

when the wavelength is smaller than the aperture:
explain:

Answer 7

less diffraction occurs

wave spreads out less

Question 8

after the waves passes through the aperture: (2)

Answer 8

-the waves spread out so they have curvature

-amplitude of the wave decreases, bc the barrier on either side of the aperture absorbs wave energy

Question 9

the wavefronts of the wave represent:

Answer 9

crests & troughs

Question 10

only property of wave that changes when it diffracts:
explain:

Answer 10

amplitude

when the wave passes through the aperture, the barrier on either side of the gap absorbs wave energy

Question 11

examples of diffraction:

Answer 11

-radio waves moving in between/around buildings

-water waves moving through a gap

Question 12

diffraction pattern of monochromatic light passing through a single slit:
explain what each part represents:

Answer 12

series of light & dark fringes on a screen

-bright fringes: maximum intensity, constructive interference

-dark fringes: minimum intensity, destructive interference

Question 13

diffraction pattern of monochromatic light passing through a single slit: explain the central maximum: (2)

Answer 13

-much wider & brighter than the other bright fringes

-on either side, much narrower & less bright maxima (get dimmer as the order increases)

Question 14

intensity pattern of monochromatic light passing through a single slit:
explain each part: (3)

Answer 14

-central bright fringe: greatest intensity, central maximum

-dark fringes: 0 intensity

-intensity of each bright fringe decreases as you move away from the central maximum

Question 15

diffraction pattern for white light passing through a single slit:
explain each part:

Answer 15

-central maximum: bright white, constructive interference from all the colours here

-all other maxima: spectrum (shortest wavelength violet would appear nearest to the central maximum bc it is diffracted less) (longest wavelength red would appear furthest from central maximum)

Question 16

explain how the colours would appear on the screen for white light passing through a single slit:

Answer 16

-shortest wavelength (violet) would appear closest to central maximum, bc it is diffracted less

-longest wavelength (red) would appear furthest from central maximum, bc it is diffracted most

Question 17

a source of white light diffracted through a single slit will produce the following intensity pattern: (5)

Answer 17

-intensity of central maxima = that of monochromatic light

-non-central maxima are wider & lower intensity

-fringe spacing between maxima gets smaller

-amount of red wavelengths in the pattern increases with increasing maxima

-amount of blue wavelengths decrease with increasing maxima

Question 18

the effects of diffraction are most prominent when:

Answer 18

aperture size ≈ wavelength of the wave

Question 19

when the wavelength passing through the gap is increased:

Answer 19

wave diffracts more

increases angle of diffraction
so width of the bright maxima also increases

Question 20

red light, which has the longest wavelength of visible light, will produce a diffraction pattern with:

Answer 20

wide fringes

Question 21

violet light, which has the shortest wavelength of visible light, will produce a diffraction pattern with:

Answer 21

narrow fringes

Question 22

if the slit was made narrower:
the intensity graph will show that: (3)

Answer 22

angle of diffraction increases
so waves spread out more

-intensity of maxima decreases
-width of central maxima increases
-spacing between fringes is wider