5. Waves Flashcards
What is a wave
Transferring energy via oscillations whilst energy moves from one place to another
Mechanical wave
Needs some sort of material medium -a substance that oscillates to allow transfer of energy
Electromagnetic waves
Transfer energy through repeated oscillations of electric or magnetic fields
Amplitude
Magnitude of the maximum displacement reached by an oscillation in the wave
Frequency
Number of of complete wave cycles per second this may sometimes be measured as the number of complete waves passing a point per second
Wavelength
Distance between a point on a wave and the same point on the next cycle of the wave for example the distance between adjacent wave peaks
. Period.
Time taken for one complete oscillation at one point on the wave this may also be the time taken for the wave to travel one wavelength
Phase
Stage a given point on a wave is for a complete cycle phase is measured in angle units as a complete wave cycle is considered to be the same was travelling around the complete circle that is 360°
Wave speed
Rate of movement of the wave
Wave speed equation
V = f X wavelength
Transverse waves
Oscillations occur perpendicular to direction of movement of the wave energy
Longitudinal waves
Oscillations occur parallel to the direction of movement of the wave energy
Compression
Area and the long that you wave in which the particle oscillations put them closer to each other than the equilibrium state
Rarefaction
Area in the long tunnel wave in which the parts cost solutions put them further apart from each other than the equilibrium state
Examples of longitudinal waves
Soundwaves
Earthquakes
Wave superposition
When waves meet each wave will be trying to cause he waved displacement at the point of intersection the net effect is that displacement will be the vector. Some of the displacement caused by the individual waves after the encounter each way will continue past each other as the energy progresses in the same direction, it originally travel.
Nodes
Regions on a stationary wave where the amplitude of oscillation is zero
Destructive interference
Antinodes
Regions of a stationary wave where the amplitude of oscillation is that its maximum
Constructive interference
Constructive interference
Superposition effect of two ways that are in phase producing larger amplitude resultant wave
Destructive interference
Superposition effect of two waves that are out of phase producing a smaller amplitude resultant wave
Wavefronts
Lines connecting points on the wave dotat exactly the same phase position
Sonometer
Apparatus for experimenting with the frequency relationships of the string and attention usually consisting of horizontal wooden sanding box and Y stretch along the top of the box
Stationary/standing wave
A wave is reflected from a boundary and meets with another wave where they both pose which creates a stationary wave
Waves need to be coherent
Coherent waves
If they have the same frequency and how it constant phase relationship coherent ways I needed to form a stable standing wave
Diffraction
Spreading over a wave energy for a gap or around an obstacle
Factors affecting diffraction
Size comparison between obstacle and wavelength of the wave
Refraction
Changing heat wave speed on the wave moves from one to another there is a corresponding changing with direction governed by Snells law
Refractive index
Result of the changing wave speed
Critical angle
Largest angle of incidents that array in a more optically dense medium can have and still emerge into less than medium beyond the Sun with the ray will be totally internally reflected
What conditions are needed to reach total internal reflection?
The race is attempting to emerge from the more dense medium
The angle between the ray and the normal to the interface is great and the critical angle
Convex lens
Converge parallel raised to a focus at the focus length from the lens
Concave lenses
Diverge parallel rail to Peter come from a virtual focus at the focal length back from the lens
Focus/focal point
Point where raise incident on the lens and parallel to the principal axis will be made to meet by the refraction of the lens
Difference between converging and diverging lens
Converging lens will bring light or a closer together
Diverging lens will spread light rays further apart
Focal length
Distance from the centre of the lens to its focal point
Real image
Can be projected onto a screen
Is on the other side of the lens from the object
Virtual image
Cannot be projected to a screen
Same side of lens as the object
Formula for magnification
Image size divided by object size
Polarisation
Orientation of the plane of oscillation of a trans wave if the wavers plain polarised all its oscillations occur in one single plane
Photons
Packets of electromagnetic radiation energy with the amount of energy which is planks concert multiplied by the frequency of the radiation
Quantisation
Concept that’s there is a minimum smallest amount by which a quantity can change infinity changes are not permitted in a quantum universe. These quantisation of a quantity is analogous to the idea of the position of an instrument measure it.
Wave particle duality
Principal that the behaviour of electromagnetic radiation can we describe in both terms of waves and photons
Photo electrons
Electrons released from a metal surface as result of its exposure to electromagnetic radiation
Work function
Minimum energy needed point an electron at the surface of a metal to escape from the metal
Threshold frequency
Given metals the minimum frequency of electron magnetic radiation that can cause the emission of electrons from the metal
Stopping voltage
Minimum voltage needed to reduce the photoelectric current to zero
What experiment can you do to suggest wave behaves as particle?
Photo Electric effect
What experiment can suggest light behaviours wave?
Young double slit experiment
Ground State
Low energy level for a system for example when all the electrons in an atom are in the lowest energy levels they can occupy the atom said to be in ground stage
Line spectrum
Series of individual lines of colour showing the frequencies present and a light source
Ionisation energy
Minimum energy are quite born electron in an atom ground state in order to remove the electron completely from the atom
Excitation
Energy state for assistant that says high energy then the ground state for example within an atom of an electron is a higher energy level than the ground state at said to be excited
Intensity
Measure of how much energy wave is carrying
Intensity
Measure of how much energy wave is carrying
Intensity is proportional to what?
Amplitude squared
Plain polarisation
Polarising a wave seated only oscillate in One Direction
Plane of Polarisation
The plane in witchy wave vibrations called diploma polarisation
What type of wave does polarisation only work on?
Transverse waves
Interface
Boundary between two different media
Critical angle
Angle of incidence in a optically dense material which the angle of a refraction is 90°
Explain why the lens with shorter focal length is thicker at centre
Greater refraction to converge parallel rays at a point closer to the lens
Why excited atoms only emit certain frequencies or radiation?
Electrons exist in discrete energy level levels
After excited electrons move back to a lower energy level
Photons are emitted
Frequency of emitted photons depend depends on difference and energy between energy level (E=hf)
Only certain energy changes are possible so only certain frequencies are possible
