Electrons, Waves and Photons Flashcards
What is Wavelength
The smallest distance between two points that have the same pattern of oscillation
What is the Time Period
The time taken for one complete pattern of oscillation to take place at any point
What is Frequency
The number of oscillations per unit time
What is displacement?
The distance any part of the wave has moved from its rest position
What is Amplitude?
The maximum displacement
What is a Progressive Wave
A wave that transfers energy as a result of oscillations of the medium through which energy is travelling without the transfer of the medium
What is a Transverse Wave
Waves where the oscillations of the particles are perpendicular to the direction of wave propagation
What is a Longitudinal Wave?
Waves where the oscillations of the particles are parallel to the direction of wave propagation
Derive the wave equation?
V = S/t-> v = distance travelled in one cycle. . time taken for one cycle —> v = lamda/ time
What are Cathode Ray Oscilloscopes
They allow the visualisation of transverse and longitudinal waves on a screen
Equation for Intensity
Intensity = Power/ Area
What is an Electromagnetic Wave?
An electromagnetic wave is a transverse wave consisting of oscillating electric and magnetic fields at right angles to each other
What is Unpolarised Wave?
Light waves in which the electric and magnetic fields vibrate in all directions perpendicular to the direction of travel of the wave
What is Plane Polarised Light?
Light waves in which the electric and magnetic fields vibrate in one direction (on a single plane) perpendicular to the direction of travel of the wave
What is the Plane of Polarisation of an electromagnetic wave?
The plane in which the electric field oscillates
What is Polarisation
The process of turning unpolarised light into polarised light
What is the Rule of Reflection?
Angle of incidence is always equal to the angle of reflection
Uses of concave surfaces
Satellite dishes
Uses of convex surfaces
Wing mirrors
What is Diffraction
The process of a wave spreading out after it has passed around an obstacle or through a skirt
When does a wave experience maximum diffraction
A high frequency (short wavelength) wave doesn’t diffract as much as a low frequent (long wavelength) wave does A wave experiences maximum diffraction when the gap is equal to its wavelength
What is intensity
Intensity is the energy per square metre per second or Power per square metre
What is Superposition
Two waves combined at the same poiny
What is the Constructive Inteference
When two waves are combined together to be completely in phase
When will a Wave constructively interfere?
If two waves arrive at a point with a path difference equal to a whole number of wavelengths they will constructively interfere- Their phase difference will be on or a multiple of 2Pi
What is Constructive Interference?
When two waves combine together in anti phase making them cancel out resulting in a quiet spot
What causes destructive interference?
If two waves arrive at a point with a path difference of a half wavelength they’ll destructively interfere their phase difference would be Pi or A multi or of (n2Pi - Pi)
What’s necessary for an observable interference patterns?
You need a coherent waves with a constant phase relationship
What is the Principle of Superposition of Waves
the total displacement of a wave is equal to the sum of the displacements of two or more coherent waves
Thomas Young Double Split
• Monochromatic Light - Produced by laser or sodium lamp• Very narrow skits to diffract light and create 2 coherent rays • Light from the slits superpower to create an interference patternConclusion • Bright fringes occur when the waves have traveled an integer number of whole wavelengths further than the other and so arrived completely in phase (constructive interference)• Dark fringes occur where one of the waves has a path difference of a half wavelength further than the other and so arrives in anti phase and destructively integers
What is a stationary wave?
A stationary wave is the result of the superposition of two waves of the same wavelength and frequency when travelling in opposition directions • They store energy they don’t transfer it
How are stationary waves produced?
1) Reflection of a progressive wave from a fixed end2) 2 progressive waves being sent from opposite directions3) Progressive waves travel from centre and are reflected from both ends
Progressive Wave
• Amplitude - All parts of the wave between a pair of nodes are in phase and on different sides they are in anti phase • Wavelengths - Minimum distance between two adjacency points in an oscillating phase • Phase Difference - The phase changes across one complete cycle of the wave • Energy transfer - Transferred in the direction of the wave
Stationary Wave
• Amplitude - Max amplitude at the antinode and then drops to zero at the nodes• Wavelength - Twice the distance between adjacent nodes - Equal to the wavelength of the waves that created it• Phase Differences - All parts of the wave have the same amplitude (assuming no energy loss to surroundings)• Energy transfer - No net energy transfer
