Unit 1 Terminology PW1 Flashcards
Electromagnetic Spectrum
the range of wavelengths that light can exist in
Luminous body
an object that emits light ex. sun
Non-luminous body
does not emit light, but reflects and absorbs it, sometimes called illuminated ex. book/desk
Incandescent
emits light when heated, the type/colour depends on temp ex. fire poker
Rectilinear propagation
light travels naturally in a straight line, unless acted upon by gravity
Transparent
objects transmit light while absorbing/reflecting ex. glass/window
Translucent
allows light to pass through, scatters and transmit light ex. frosted window
Opaque
an object either absorbs or reflects specific wavelengths ex, desk/book
Rays
A way to represent light on paper, doesn’t actually exist in nature
Beam
a collection or rays
Shadows
when an opaque object blocks the light
Umbra
A total shadow, crisp outlines
Penumbra
A partial shadow, fuzzy outlines
Wave
the transfer of energy in the form of a disturbance propagating through a medium
Transverse Waves
occur when the vibration of the medium if perpendicular to the direction of the energy transfer
Crest
the maximum position of a transverse wave
Trough
the minimum position of a transverse wave
Amplitude
the maximum displacement from the equilibrium
Equilibrium
the point of balance, rest position
Wavelength
the distance between successive crests or troughs, represented by lambda
Longitudinal Waves
occur when the medium vibrates parallel to the direction of energy transfer, caused by the compressing and recoiling of the particles
Compressions
regions with little space between particles
Rarefactions
areas where particles are more spaced out
Pulse
a wave with a short duration
Cycle
one complete passing of a wave
Periodic Motion
waves that vibrate in repeating cycles, also called harmonic motion
Frequency (f)
the number of cycles passing by a certain point in a certain time, represented by Hz
Period (T)
the time required for a full wave to pass by a certain point
Intensity
related to wavelength and frequency, the longer the wavelength and smaller the frequency the less the intensity
Universal Wave Equation
the relationship between speed, frequency, and wavelength. Applies to all waves, even those that aren’t electromagnetic. V=flambda
Transmission
the process of a wave transferring it’s energy from one medium to another. The frequency remains the same.
Reflection
A wave is reflected back in it’s original direction
Fixed-end reflection
The wave will bounce back in the original direction but inverted.
Damping
When the amplitude of the returning wave is smaller than that of the original. Some energy is lost to the barrier.
Free-end Reflection
The wave returns in it’s original direction not inverted.
Partial Reflection
Occurs at the boundary, some of the energy in transmitted.
Interference
When two or more waves act simultaneously on a medium.
Principle of Superposition
When two or more waves pass through each other the displacement can be found by adding those of each wave.
Constructive Interference
Occurs when the resulting disturbance is greater than the individual disturbance.
Destructive Interference
Occurs when the resulting disturbance is smaller than the individual disturbances.
Standing Wave
A interference pattern with both maximum constructive and destructive interferences. Appears in such a way that looks as though the wave doesn’t move along the string.
Nodes
The points where the medium meets the equilibrium
Antinodes
The top/bottom point of crests or troughs.
Rules of Standing Waves
- There must be two or more waves of the same frequency. One or both must be a reflected wave.
- There must either be a whole or half number of wavelengths.
