P3: Light Waves, Lenses Flashcards
Theories of light
- wave theory
- particle theory
- quantum theory
what is the quantum theory of light?
light is both particle-like as well as wave-like in nature
in the particle theory each (1)_________ is a (2)___________ of energy known as a (3)___________.
- wave pulse
- packet
- photon
what is a photon
a packet oe electromegnetic energy
general wave equation
1 - medium one
2- medium two
What is an angle of incidence?
The angle between the incident ray and the normal.
What is an angle of reflection?
The angle between the reflected ray and the normal.
what are the laws of refraction?
- The angle of incidence equals the angle of reflection.
- the ratio sin(i)/sin(r) is a constant for a pair of media
What are the laws of reflection?
- The angle of incidence equals the angle of reflection.
- the incident ray, reflected ray and the normal at the point of incidence are all on the same plane
What is a plane mirror?
A perfectly flat mirror.
What is a virtual image?
An upright and laterally inverted image.
How is a real image formed?
Focusing light onto a screen.
What is refraction?
The change of direction of waves when they travel across a boundary between 2 media of different optical densitities
What happens to a light ray when it travels from air to glass?
The angle of refraction is less than the angle of incidence. The ray travels towards the normal.
What happens to the speed of a light ray when travelling from glass into air?
it increases
What is diffraction?
The spread of waves when passing through a gap or round the edge of an obstacle.
How does the width of the gap effect the diffraction of waves?
The narrower the gap is, the greater the diffraction.
Why can radio and TV reception be poor in hilly areas?
If the radio waves do not diffract enough, the waves won’t reach the aerial on a house.
How does diffraction effect optical imaging?
If light diffracts too much, the image is of poor quality.
diffraction does not affect the (1)___________, (2) ______________, (3)_______________ , or the (4)________________ of light
- speed
- wavelenght
- period
- frequency
what is interference
phenomenon which occurs at a point where 2 or more waves superpose on each other to produce a combined vibration of amplitude lesser or greater any of the individual waves
constructive interference
phenomenon which occurs at a point where 2 or more waves superimpose in phase to produce a combined vibration of amplitude greater any of the individual waves
constructive interfrence occurs where 2 or more (1)_________ or (2)________ of transverse waves meet , or where 2 or more (3)_________ or (4)__________ of (5)__________ waves meet
- crest
- troughs
- compressions
- rarefractions
- longitudinal
destructive interference occurs where (1)_________ meets (2)________ of transverse waves meet , or (3)_________ meet (4)__________ of (5)__________ waves meet
- crests
- troughs
- compressions
- rarefractions
- longitudinal
displacement is a (1)_________ quantity and is the sum of the (2)________ of the individual waves being superposed. It can be (3)_________ or (4)___________.
- vector
- amplitude
- positive
- negative
two waves of amplitudes of 3mm are superposed in phase. The result is (1)___________ interference and the resulting amplitude is (2)____________
- constructive
- 6mm
two waves of amplitudes of 3mm are superposed in antiphase. The result is (1)___________ interference and the resulting amplitude is (2)____________
- destructive
- 0mm
Give four characteristics of a reflected image
- Objects are the same size
- Same distance away from the mirror
- The image is virtual
- Laterally inverted - left and right sides are swapped.
What is refraction?
The bending (changing direction) of a light ray as it travels from one transparent substance to another one with different optical density
What happens when a ray of light enters a more optically dense substance?
It bends towards the normal
What happens when a ray of light enter a less optically dense substance?
It bends away from the normal
Will a refracted ray ever bend beyond the normal?
No (so there is no bending when a ray crosses a boundary at a right angle)
What is the relationship between sin(i) sin(r) and the refractive index(η )
sin(i) / sin(r) = η
what does this image show?
the phenomenon of diffraction
What is Snell’s Law?
When an incident ray passes into a material: n = sin(i) / sin(r) When you divide sin(i) by sin(r) you get the same number (for a particular transparent substance)
in the diagram each wave that passes through the hole is being (1)____________. the lines represent the (2)____________ and the space between the lines represent the (3)___________. The phenomenon that occurs where the waves meet is called (4)_____________. Therefore determin what occurs at: A, B, C, D, E, F,
- diffracted
- cest
- troughs
- interference
A - destructive interference, B- constructive interference, C destructive interference, D- destructive interference, E- constructive interference, F- destructive interference
What happens when a ray of white light passes through a prism?
The white light emerges as a band of colours called a spectrum. This is caused because light is a mixture of colours and each colour travels through the prism at a slightly different speed, so each colour is refracted at a different angle. The prism has a different refractive index for each colour. This process is called dispersion.
What is total internal reflection used in?
Prisms in periscopes, binoculars and bicycle reflectors, optic fibres
When does total internal reflection happen?
When you go from a more optically dense object to a less optically dense object and when the angle of incidence is greater than the critical angle