Topic 5: Wave and Particle Nature of Light
0.5 Specification notice:
In order to develop their practical skills, students should be encouraged
to carry out a range of practical experiments related to this topic. Possible
experiments include determining the refractive index of solids and liquids,
measuring the focal length of a lens, and using models of structures to
investigate stress concentrations.
Mathematical skills that could be developed in this topic include using
calculators to handle sin x, identifying uncertainties in measurements and
using simple techniques to determine uncertainty when data are
combined.
This topic may be studied using applications that relate to waves and
light, for example medical physics.
5.Q Exam questions
● Two connected dippers above the
water (1)
● Vibrated electrically (1)
● Shallow water (1)
● Illuminate using stroboscope (1)
Describe how such a pattern could be
produced and observed using a ripple tank.
(5)
,On the diagram draw the following
1. A line labelled A joining points
where the waves from S1 and S2
have travelled equal distances
2. A line labelled B joining points
where the waves from S1 have
travelled one wavelength further
than the waves from S2
3. A line labelled C joining points
where the waves from S2 have
traveleed half a wavelength further
than the waves from S1
1. Decrease
2. Increase
3. Increase
, 1. If only the separation of the sources
were increased, the angle between
A and B would __________
2. If only the wavelength of the waves
were increased, the angle between
lines A and B would__________
3. If only the depth of the water in the
ripple tank were increased, the
angle between A and B
would_________
A monochromatic beam of light of
wavelength λ from a laser is directed at a
diffraction grating of line spacing d. ● C is answer
A student calculates the value of d/λ in order
to determine the expected number of visible
maxima.
The calculated value of d/λ is 4.7
How many maxima are visible?
5.59 Understand the terms amplitude, frequency, period,
speed and wavelength
What is amplitude? The maximum displacement of a wave
from rest position
What is frequency (in terms of waves)? The number of waves produced by a
source each second
, What is time period? The time taken for one complete
wavelength to pass a point
What is speed? The distance travelled per unit time
What is wavelength? The distance between two identical
consecutive points
At what wavelengths does visible light lie? 400nm to 700nm
5.60 Be able to use the wave equation v = fλ
What is the wave equation? v = fλ
5.61 Be able to describe longitudinal waves in terms of
pressure variation and the displacement of molecules
What is a longitudinal wave? And Examples The direction of oscillations are parallel
to the direction of energy
propagation
Examples: Seismic P-waves and sound
What are areas of high pressure called on a Compressions
longitudinal wave?
What are areas of low pressure called on a Rarefactions
longitudinal wave?
What are mechanical waves (with Waves that rely on a medium to travel
examples)? through
0.5 Specification notice:
In order to develop their practical skills, students should be encouraged
to carry out a range of practical experiments related to this topic. Possible
experiments include determining the refractive index of solids and liquids,
measuring the focal length of a lens, and using models of structures to
investigate stress concentrations.
Mathematical skills that could be developed in this topic include using
calculators to handle sin x, identifying uncertainties in measurements and
using simple techniques to determine uncertainty when data are
combined.
This topic may be studied using applications that relate to waves and
light, for example medical physics.
5.Q Exam questions
● Two connected dippers above the
water (1)
● Vibrated electrically (1)
● Shallow water (1)
● Illuminate using stroboscope (1)
Describe how such a pattern could be
produced and observed using a ripple tank.
(5)
,On the diagram draw the following
1. A line labelled A joining points
where the waves from S1 and S2
have travelled equal distances
2. A line labelled B joining points
where the waves from S1 have
travelled one wavelength further
than the waves from S2
3. A line labelled C joining points
where the waves from S2 have
traveleed half a wavelength further
than the waves from S1
1. Decrease
2. Increase
3. Increase
, 1. If only the separation of the sources
were increased, the angle between
A and B would __________
2. If only the wavelength of the waves
were increased, the angle between
lines A and B would__________
3. If only the depth of the water in the
ripple tank were increased, the
angle between A and B
would_________
A monochromatic beam of light of
wavelength λ from a laser is directed at a
diffraction grating of line spacing d. ● C is answer
A student calculates the value of d/λ in order
to determine the expected number of visible
maxima.
The calculated value of d/λ is 4.7
How many maxima are visible?
5.59 Understand the terms amplitude, frequency, period,
speed and wavelength
What is amplitude? The maximum displacement of a wave
from rest position
What is frequency (in terms of waves)? The number of waves produced by a
source each second
, What is time period? The time taken for one complete
wavelength to pass a point
What is speed? The distance travelled per unit time
What is wavelength? The distance between two identical
consecutive points
At what wavelengths does visible light lie? 400nm to 700nm
5.60 Be able to use the wave equation v = fλ
What is the wave equation? v = fλ
5.61 Be able to describe longitudinal waves in terms of
pressure variation and the displacement of molecules
What is a longitudinal wave? And Examples The direction of oscillations are parallel
to the direction of energy
propagation
Examples: Seismic P-waves and sound
What are areas of high pressure called on a Compressions
longitudinal wave?
What are areas of low pressure called on a Rarefactions
longitudinal wave?
What are mechanical waves (with Waves that rely on a medium to travel
examples)? through
