4.4 - Waves Flashcards
What is a Progressive Wave?
A wave that transfers energy away from a source
What is a Longitudinal Wave?
A wave where the oscillations are parallel to the direction of wave propagation
What is a Transverse Wave?
A wave where the oscillations are perpendicular to the direction of wave propagation
What is Wavelength?
The distance between two successive identical points that have the same pattern of oscillation. Measured in metres.
What is Period?
The period of a wave is the time it takes for one complete pattern of oscillation to take place at any point. Measured in seconds
What is Frequency?
The number of oscillations per unit time at any point. Measured in Hertz
What is Displacement?
The distance any part of the wave has moved from its rest position
What is Amplitude?
The maximum displacement of a wave from its rest position
What is Phase Difference?
It concerns the relationship between the pattern of vibration at two points.
What is the standard wave length of Radio and Microwaves?
Radio - 10^-1 - 10^4
Microwave - 10^-4 - 10^-1
What is the standard wave length for Infra Red and Visible Light waves?
Infra Red - 7.4x10^-7 - 10^-3
Visible Light - 3.7x10^-7 - 7.4x10^-7
What are the standard wavelength for Ultra Violet, X-Rays and Gamma Ray waves?
Ultra Violet - 10^-9 - 3.7x10^-7
X-Rays - 10^-12 - 10^-7
Gamma Rays - 10^-16 - 10^-9
What is the Intensity of a progressive wave?
The rate at which energy is transferred from one location to another as the wave travels through space, perpendicular to the direction of wave travel. I=P/A
What is Diffraction?
The spreading out of a wave after passing around an obstacle or through a gap
How does a polarising filter produce plane-polarised light?
By selective absorption of one component of the incident oscillations - the filter transmits only the component of light polarised perpendicular to that direction
What is a plane-polarised wave?
A wave in which the oscillations of the field and the direction of travel are confined to a single plane
What is the principle of superposition?
When two or more waves of the same type meet, the resultant wave can be found by adding the displacements of the individual waves
What is coherence?
Two waves with a constant phase relationship
What is the order?
The number pattern, n, on either side of the central maximum
What are nodes?
Points in a stationary wave at which there is no displacement of the particles at any time
What is an antinode?
Points where the displacement of the particles in a stationary wave varies by the maximum amount
When can we observe total internal reflection?
When light or an other electromagnetic radiation travels from a material of a higher refractive index to one of lower refractive index (I.e. water to air) and the angle of incidence is larger than the critical angle
How do you find the period of a wave on an oscilloscope?
Distance between peaks x time base setting
What does each horizontal division on an oscilloscope represent?
A unit of time
What does each vertical division on an oscilloscope represent?
A unit of voltage
What is Malus’ Law?
It states that when a perfect polariser is put in a beam of polarised light, the intensity, I, of the the light that passes through is given by I=I(max)cos^2x
What is polarisation used for?
Stress Analysis, Sunglasses (reflected and scattered light) and Radio Transmission
