Shared Flashcard Set

Details

Introduction to Physics for Life Sciences
University of Guelph PHYS*1070
268
Physics
Undergraduate 1
04/13/2015

Additional Physics Flashcards

 


 

Cards

Term
β-
Definition

0-1e

A form of β radiation. An electron. One antineutrino is released as well. 

Term
β+
Definition

01e

A form of β radiation. A positron. One antineutrino is released as well.

Term
σ-electron
Definition
An electron near the centre of the atom. Localized on their atoms; do not move or enter the light-absorption process.
Term
π-electron
Definition
An electron involved in covalent bonds. Can move freely along the molecule through covalent bonds.
Term
Absorbance
Definition
Energy is transfered. Measured by a spectrophotometer.
Term
Absorption cross-section (σ)
Definition
The fraction of radiation absorbed per unit concentration per unit distance.
Term
Absorption spectrum
Definition
A graph of absorbance over a range of wavelegths.
Term
Accommodation
Definition
The ability to focus the crystalline lens in the eye to fous on objects of varying distances.
Term
Acoustic resonance
Definition
When the wavelength is exactly proportional to the size of a container, making a harmonic (first, second, et cetera). CAn be set up in any container, including rooms.
Term
Acuity
Definition
The ability of the eye to resolve small objects. Measured with a Snellen Chart.
Term
Airy disc
Definition
Diffraction pattern. A ringed pattern that light maes when it passes through a small aperture.
Term
Alpha (α) radiation
Definition

42He

A radioactive emission. Nucleus of helium atoms. Well-defined energies. High mass and charge makes them easy to shield against; a sheet of paper will suffice. Alpha-emitters are long-lived. Alpha particles travel in a straight line. Deposit energy near the end of their path.

Term
Amacrine cells
Definition
Cells under the ganglion cells in the eye. There are no amacrine cells in the fovea.
Term
Ampere (A)
Definition
The unit that electric current is measured in.
Term
Amplitude (A)
Definition
The maximm distance that a mass can oscillate away from the equilibrium position.
Term
Angular frequency (ω)
Definition
Measured in radians per second.
Term
Anterior chamber
Definition
The part of the eye in front of the ciliary muscle.
Term
Antineutrino (v bar)
Definition
A particle released along with β radiation. Shares some of the energy released. Lacks mass or charge, and travels very near the speed of light.
Term
Antinode
Definition
Positions in a standing wave where the maximum displacement occurs at various times.
Term
Anvil
Definition
A bone in the middle ear. Vibrated by the eardrum.
Term
Aqueous humor
Definition
A transparent fluid that fills the crystalline lens. At higher pressure than the vitreous humor.
Term
Astigmatism
Definition
When the eye cannot focus clearly on horizontal and vertical lines simultaneously. The surface of the cornea is not spherical; more sharply curved in one plane than another. There are two focus lengths. One image axis is in focus while the perpendicular axis is not. Corrected with cylindrical lenses that bring the two axis into coincidence.
Term
Attenuation
Definition

When energy is lost due to friction with air molecules. In this course we assume that there is no attenuation in waves.

Radiation diminishes in intensity with distance.

Term
Auditory canal
Definition
A part of the outer ear. A 2.5 cm long air-filled canal through which sound waves travel to the eardrum.
Term
Auricle
Definition
A part of the outer ear. The visible part of the ear that helps determine the direction of the source of sound, and guides sound waves into the auditory canal.
Term
Basilar membrane
Definition

aka Base membrane

A membrane between the two chambers in the cochlea. Vibrates when sound waves are in the cochlear fluid. The outer and inner hair cells are found in regions on the basilar membrane. When the membrane vibrates they stimulate the tectorial membrane.

Term
Beat frequency
Definition
The frequency of loud periods in beats.
Term
Beats
Definition
When interference alternates between destrictive and constructive at regular intervals.
Term
Beer-Lambert Law
Definition

aka Beer's Law

I(λ) = I0(λ)e-σCx = I0(λ)e-μx

Term
Bell
Definition
The circumference of a bell is equal to one λ.
Term
Benzene
Definition
A ring-shaped chromophore with 6 π-electrons.
Term
Beta (β) radiation
Definition
A radioactive emission. Energy is on a continuous spectrum of energies from zero to a maximum. Travel about 3 meters in air or water. Can do damage to tissues. Easy to sheild against: a 1 cm sheet of plastic will suffice. Smaller mass than alpha particles more easily deviated form their path. Includes β- and β+ particles.
Term
Binaural beats
Definition
When a person has one frequency played in one ear and a different frequency played in the other, even through the two sound waves do not come into contact, the person can hear the beats that would have occured between the two waves.
Term
Binocular parallax
Definition
Two eyes perceiving slightly different images and the brain meshing the images together to give depth perception.
Term
Binocular vision
Definition
Having two eyes. In humans, the field of view of the eyes overlaps for 170º.
Term
Biological half-life
Definition
The time it takes for a body to expel by excretion, perspiration, exhalation, etc. half of a substance from the body.
Term
Bipolar cells
Definition
Cells in the eye which have contact with ganglion, amacrine, and horizontal cells.
Term
Blackbody radiation
Definition
Light emitted from very hot objects.
Term
Carbon radiation
Definition
The production and detection of 14C to determine the age of an object.
Term
Chromatic aberration
Definition
Refractive index differs slightly with the wavelength of light. Eyes naturaly experience chromatic aberration but we are unaffected by it. Higher in dim light when we are more sensitive to blue-green. Double lenses may be used to compensate for various wavelengths.
Term
Ciliary muscle
Definition
Part of the eye. Attached to the crystalline lens. Divides the eye into the anterior chamber and posterior chamber. Dilates the crystalline lense to focus the lens, giving accommodation.
Term
Cochlea
Definition
A snail shell-shaped chamber of the inner ear. There are two fluid-filled chambers within, one that ends in the oval window and the other with the round window. The chambers are separated by the Reissner's membrane, basilar membrane, and tectorial membrane.
Term
Coloumb (C)
Definition
The SI unit for electrical charge.
Term
Coloumb constant (k)
Definition
8988 x 109 N•m2/C2
Term
Coloumb's Law
Definition
F = (k |q1q2|) / (Kr2)
Term
Compound microscope
Definition
Uses two lenses to view cell-sized structures. Produces a virtual, inverted, and greatly magnified image.
Term
Compton scattering
Definition
At high energies, energy collides with an electron, sending it away at angle θ, and bouncing of at angle Φ with less energy.
Term
Conductors
Definition
Materials with low resistivity.
Term
Cones
Definition
Cone-shaped photoreceptor cells in the retina. In the fovea they respond best to red (575 nm) and green (545 nm) light and are responsible for photopic vision. In the peripheral retina they respond best to blue (450 nm) light and are responsible for scotopic vision.
Term
Constructive interference
Definition
When the crests and troughs  of the two waves in a standing wave coincide with one nother. They add together, forming supercrests and supertroughs.
Term
Cornea
Definition
A slight bulge on the front of the eye where light enters.
Term
Crest
Definition
A maximum point in a wave.
Term
Crystalline lens
Definition
Part of an eye. The space between the cornea and the rest of the eye. Filled with aqueous humor. The anterior edge has a radius of curvature of 10 mm. The posterior surface has a radius of curvature of 6 mm.
Term
Converging lens
Definition

aka Positive lens

Power is positive. Thicker in the centre than at the edges. Corrects hypermetropia.

Term
Current density (J)
Definition
Current per unit area flowing across a surface that is at right angles to the flow.
Term
Cyclic molecules
Definition
Molecules where π-electrons can go either way around a ring (sine and cosine), so there can be 4 electrons in each n level, except for n = 0, which can only have 2.
Term
Cylindrical lens
Definition
Corrects astigmatism. A lens that has no curvature in one plane, and sufficient curvature in another plane.
Term
Dampened harmonic motion
Definition
SHM with friction. The amplitude decreases over time, but the period stays constant.
Term
Decay constant (λ)
Definition
The probability that a nucleus will decay within a unit of time.
Term
Decibels (dB)
Definition
The unit that intensity level is measured in.
Term
Density (ρ)
Definition
The mass density of a substance. Measured in kilograms per meter cubed.
Term
Destructive interference
Definition
When the crests and troughs of the two waves in a standing wave cancel each other out.
Term
Detector
Definition
A component of a spectrophotometer. A photocell, photodiode, or photomultiplier that produces electrical curent proprtional to the power of light falling on it, and displays this on a meter or records it on a computer as an absorbance or percent transmittance.
Term
Dielectric constant (K)
Definition
A dimensionless quantity that is a property of the material where E is measured.
Term
Diffraction
Definition
The bending of light by obstacles. Occurs when light passes through small apertures.
Term
Diffraction grating
Definition
A type of monochromator. A mirror with fine grooves that spreads light according to wavelength.
Term
Diopters (D)
Definition
The unit that optical power is measured in. The value for power when r is measured in meters.
Term
Diverging lens
Definition

aka Negative lens

Power is negative. Thinner in the centre than at the edges. Corrects myopia.

Term
Dose (D)
Definition
The amount of energy deposited by radiation per unit mass. Expressed in grays or ra.
Term
Duplex retina
Definition
Organization of the retina into two functional regions.
Term
Ear
Definition
The organ that detects sound waves and produces neural signals that are interprested by the brain, giving the perception of sound. Includes the outer ear, middle ear, and inner ear.
Term
Eardrum
Definition

aka Tympanic membrane

A part of the outer ear. Vibrates when hit with sound waves, moving the bones of the middle ear.

Term
Effective decay constant
Definition
The physical decay constant plus the biological decay constant.
Term
Effective dose (E)
Definition
The dose of radiation, taking into account the sensitivity of tissues.
Term
Einstein's photoelectric equaion
Definition
Vs = (hf / e) - (Φ / e), if f ≥ 0
Term
Elastic potential energy (U)
Definition
The energy stored in an object as a result of twisting, stretching, or compressing. Example: energy stored in a spring.
Term
Electric current (I)
Definition
Measured in amperes. The force developed between parallel wires carrying a specific current.
Term
Electric field (E)
Definition

The forces exerted betwen two separate charges.

E = (k |q|) / (Kr2)

Term
Electric potential (V)
Definition

V = kq/Kr

Measured in volts.

Term
Electric potential energy
Definition
Equal to the work done to displace charged particles in an electric field.
Term
Electromagnetic (EM) wave
Definition

aka Light

A transverse wave of electric and magnetic fields, generated when electric charges are accelerated. No material particle is involved. Can carry energy through a vacuum, including outer space. In a vacuum EM waves travel at c, 3.998 x 108 m/s. Electric and magnetic waves are transverse waves perpendicular to each other and to the direction of travel.

Term
Electron-positron pair production
Definition
A gamma ray with at least 1.02 MeV of energy produces an electron and a positron.
Term
Electron spin
Definition
Electrons have two possible states, symbolized by the spin quantum number: -½ or +½.
Term
Electron volt (eV)
Definition
A unit of energy equal to 1.602 x 10-19 J. The kinetic energy acquired by a single electron startnig from rest an accelerating through a potential differene of one volt.
Term
Electron state diagram
Definition
A diagram of lines each representing an n state, with up to 2 arrows in each level representing electrons in each n state.
Term
Energy
Definition
Power over time. Measured in Joules.
Term
Energy density (Ev)
Definition
The energy per molecule, multiplied by the numer of molecules per unit volume. Measured in joules per meters cubed.
Term
Energy level diagram
Definition
An electronic state diagram where the electrons' energies are represented to scale.
Term
Equilibrium position
Definition

x = 0

The resting position of an object in SHM. At this point, no force is being exerted on the mass.

Term
Equivalent dose (H)
Definition
The measure of biological damage of radiation.
Term
Erect imge
Definition
When the image has a right-side-up orientation compared to the object. Magnification is positive.
Term
Excited molecules
Definition
Higher in electronic state.
Term
Excited state
Definition
States in which one or more of the electrons do not have their lowest n value.
Term
Far-point
Definition
The object distance farthest from the eye for which the image can be clearly brought into focus on the retina. In a normal eye it is infinity.
Term
First harmonic
Definition

When there is one node in a standing wave.

For a double-open ended pipe, λ = 2(length)

For a blocked pipe, λ = 2(length)

Term
Fluorescence
Definition
When a molecule has vibrational relaxation, it radiates a photon with energy hf. Energy of the photon is equal to or less than the energy of the absorbed photon. The wavelength is longer than the absorbed light. Takes about 10-7 seconds.
Term
Focal length (f)
Definition
The position where the image is formed of a very ditant object (p → ∞). A property of a lens.
Term
Force (F)
Definition
Measured in Newtons (N).
Term
Force constant (k)
Definition
Force per unit of displacement of a spring. Always positive. Stiffer springs have a higher number than loose springs. Measured in Newtons per meter (N/m).
Term
Forced harmonic motion
Definition
Oscillation where the force on the object varies periodically. The period of the force determines the frequency of oscillation; can be any frequency. If the frequency is not the resonance frequency, it is difficult to have a large amplitude.
Term
Fourier's Theorum
Definition
Any periodic wave function can be made from a sum of sine and cosine waves.
Term
Fovea
Definition
The spot on the retina where the visual axis hits the retina. Has high acuity of vision. Responsible for focusing on objects closely. Contains only cone cells, and lacks horizontal and amacrine cells.
Term
Franck-Condon Principle
Definition
When a molecule makes a tansition to a higher electronic state, it usually also makes a transition to a higher vibrational state. It heats up.
Term
Free radicles
Definition
H and OH molecules created when radiation hits a water molecule. Very chemically reactive.
Term
Frequency (f)
Definition
The number of complete oscillatons occurring in one second. Measured in Hertz (s-1)
Term
Friction
Definition
Causes dampened harmonic motion. If friction is strong, the object will not oscillate, just return to equilibrium position.
Term
Fundamental vibrational transition
Definition
The v=0 → v=1 transition in vibrational levels. Absorbs the wavelength for vibration.
Term
Gamma (γ) radiation
Definition
A radioactive emission. Electromagnetic wave of a very short wavelength. High energy; around 1 MeV. After alpha or beta particle emission, the nucleus is left with excess energy which is emitted as a gamma ray. Hard to protect from; several centimeters of lead would suffice. Penetration depth and range does not apply.
Term
Gamma-rays
Definition

λ = 10-12 m

aka Ionizing radiation

eM waves with the shortest wavelength and highest energy. Can produce significant damage in living systems at the molecular level.

Term
Ganglion cells
Definition
Located at the surface of the retina where light first hits.
Term
Grays (Gy)
Definition

The unit that radiation dose is measured in.

1 Gy = 1 J/kg

Term
Ground state
Definition
The electron configuration of the lowest energy.
Term
Half-life (T½)
Definition
The time for any given starting amount to decrease to half of that amount.
Term
Hammer
Definition
A bone in the middle ear. Vibrated by the eardrum.
Term
Horizontal cells
Definition
Located under the ganglion cells in the eye. There are no horizontal cells in the fovea.
Term
Hot molecules
Definition
Higher in vibrational state.
Term
Hypermetropia
Definition

aka Far-sightedness

Sharp images of objects fall beyond the retina. The near point is greater than 25 cm. Corrected with a positive power. Sometimes lenses of differing powers are needed for distant, intermediate, and close-up objects. Bifocal and trifocal lenses may be used.

Term
Image distance (q)
Definition
Positive when the direction from the optical surface to the images is with the flow of light.
Term
In phase
Definition
When two objects are oscillating with the same period and phase angle and pass through equilibrium position at the same tie. Amplitudes may differ.
Term
Infrared
Definition

10-7m < λ < 10-3m

aka Heat radiation

EM waves. Will denature proteins.

Term
Inner ear
Definition
Where neural signals originate in the ear. Includes the cochlea. Vibrations come in through the oval window.
Term
Insulators
Definition
Materials with high resistivity.
Term
Intensity (I)
Definition
The power of a wave carried across a unit of area.
Term
Intensity level (IL)
Definition
A logarithmic scale for intensity. Measured in decibels.
Term
Interference
Definition
Waves interacting with destructive or constructive interference. May create beats.
Term
Inverse square law
Definition
Intensity is inversely correlated with distance from the source of sound.
Term
Inverted image
Definition
Magnification is negative. When the image has an upside-down orientation to the object.
Term
Ionizing radiation
Definition
X-ray or gamma-ray radiation. So energetic that they break molecular bonds.
Term
Iris
Definition
Part of the eye in front of the cornea. Adjusts the amount of light entering the eye.
Term
Joules (J)
Definition
A unit that energy is measured in.
Term
Kirchhoff's loop rule
Definition
The total change in electric potential around any closed loop in a circuit is zero.
Term
Kirchhoff's point rule
Definition
The total current entering a point in a circuit must equal the total current leaving the point.
Term
Lateral geniculate nucleus
Definition
The area of the brain that the optic nerve is attached to.
Term
Linear absorption coefficient (μ)
Definition

μ = σC

The fraction of radiation absorbed per unit distance.

Term
Linear attenuation coefficient (μ)
Definition
A parameter that includes the effects of scattering and absorption.
Term
Linear chromophores
Definition
There can be two electrons per n level.
Term
Linear energy transfer (LET)
Definition
dE / dx
Term
Longitudinal wave
Definition
A wave where the oscillation occurs parallel to the diretion of travel. Example: a sound wave.
Term
Loudness
Definition
The intensity of sound as percieved by human ears.
Term
Magnification (M)
Definition
The relation between object size and image size. Positive when the image is erect. Negative when the image is inverted.
Term
Mass attenuation coefficient (μmρ)
Definition
The linear attenuation coefficeint in a substance with density ρ.
Term
Meters (m)
Definition
A unit that position is measured in.
Term
Microwaves
Definition
Radio waves with lower wavelengths, close to λ = 1 mm. Will heat water.
Term
Middle ear
Definition
Includes the bones the hammer, anvil, and stirrup, and the oval window. Acts as a pressure amplifier.
Term
Monochromator
Definition
A component of a spectrophotometer. Allows a narrow band of wavelengths to pass through. Commonly uses a diffraction grating.
Term
Myopia
Definition

aka Near-sightedness

Sharp images of objects fall in front of the retina. Corrected with a lens with a negative power.

Term
Near-point
Definition
The object distance closest to the eye for which an image can be clearly brought into focus on the retina. In normal eyes it is about 25 cm.
Term
Newtons (N)
Definition
A unit that force is measured in.
Term
Node
Definition
Positions in a standing wave where there is no displacement at any time. Distance betwen nodes is ½λ.
Term
Normal
Definition
A right angle from the interface between two transparent substances. Angles in calculations are in relation to the normal.
Term
Numerical aperture
Definition

n sin θ

A characteristic of a lens. A factor in calculating the resolvable separation of microscopes. Good microscope objective lenses have a numerical aperture of 0.5.

Term
Objective distance (p)
Definition
Positive when the direction from the optical suraface to the object is against the flow of light.
Term
Ohm (Ω)
Definition

1 Ω = V/A

The SI unit of resistance.

Term
Ohm's law
Definition
ΔV = IR
Term
Ohmic
Definition
When a material has a constant resistance.
Term
Optic nerve
Definition
Where the nerve fibres in the retina converge. 15º below the fovea. Lacks photoreceptors, creating a blind spot.
Term
Oscillation
Definition
Back-and-forth motion.
Term
Outer and inner hair cells
Definition
Hairs anchored to the basilar membrane so that the tips are close to the tectorial membrane. Vibrations in different regions create neural signals.
Term
Outer ear
Definition

aka External ear

Includes the auricle, auditory canal, and the eardrum.

Term
Outer segments
Definition
Light-sensitive parts of photoreceptor cells in the retina. Face towards the pigment epithelium.
Term
Oval window
Definition
Part of the middle ear. Vibrations are translated into the inner ear.
Term
Panoramic vision
Definition
When there is no overlap between the field of view of hte two eyes. Chameleons, for example, have panoramic vision.
Term
Parallel
Definition
A circuit where the current flows through all resistors at once.
Term
Pauli Exclusion Principle
Definition
In a given molecule, no two electrons may share the exact same quantum numbers.
Term
Pendulum
Definition
An example of harmonic motion.
Term
Perfect pitch
Definition
The ability to accurately identify the frequencies of sounds. Most humans can only determine the relation of one pitch to another.
Term
Period (T)
Definition
The time of one complete oscillation. Measured in seconds.
Term
Peripheral retina
Definition
The part of the retina far from the fovea. Responsible for peripheral vision.
Term
Phase angle (δ)
Definition

A dimensionless constant. Depends on the point in the cycle where t is arbitrarily chosen to be zero.

When t = 0, δ = 0

 

Term
Phosphorescence
Definition
When a molecule enters triplet state, the molecule must wait for the electron to flip spin number before it can have vibrational relaxation and fluorescence. The photon released has much lower energy and longer wavelength than the absorbed photon. Takes much longer than fluorescence.
Term
Photoelectric effect
Definition
EM waves causing electrons to be ejected from a metal. Energy interacts with an orbital electron, ejecting it with an energy equal to the difference between gamma ray energy and the electron's binding energy.
Term
Photon
Definition

aka Quanta

An indivisible lump of a light wave. Has differing amonts of energy, depending on the wavelength of light.

Term
Photopic vision
Definition

aka Day vision

Can sense colour. Cone cells in the fovea are responsible for photopic vision.

Term
Photoreceptor cells
Definition
Found in the retina of the eye. Include rods and cones.
Term
Pigment epithelium
Definition
A light absorbing black layer below the retina. In cats and other animals it is reflective, causing their eyes to appear to light up when a light is shone on their eyes in the dark.
Term
Pipes
Definition
If closed off at one end, a pipe has acoustic standing waves; a node occurs at the closed end and an antinode at the open end. The length of the tube is ¼λ.
Term
Pitch
Definition
The frequency of sound as perceived by human ears.
Term
Plane polarized
Definition
Light that has been sorted so that there are only EM waves of a specific polarization.
Term
Plane waves
Definition
Waves that travel only in one direction. Intensity is a constant.
Term
Polarization
Definition
The direction in space in which the electric field vector of an EM wave is pointing. Some insects can sense the polarization of light.
Term
Porphyrin
Definition
A ring-shaped chromophore with 20 π-electrons. Found in chlorophyll, hemoglobin, myoglobin, and others. Bond length = 0.12 nm.
Term
Position (x)
Definition
Measured in meters.
Term
Positive charge test
Definition
Determines the direction of an electric field vector. Exposed to a positive charge.
Term
Positron
Definition

01e

A positive electron.

Term
Posterior chamber
Definition
The part of the eye behind the ciliary muscle. Filled with vitreous humor.
Term
Power (energy)
Definition
Energy over time. Measured in Watts.
Term
Power (lenses)
Definition
A measure of the focusing ability of a lens. Measured in diopters. A positive number indicates a converging lens, and a negative number indicates a diverging lens.
Term
Presbyopia
Definition
A hardening of the crystalline lens as a person ages, reducing ability of accommodation.
Term
Principle of wave of superposition
Definition
The displacement of a standing wave is the sum of the displacements of the two waves y1 and y2.
Term
Probability density (P)
Definition
The likelihood that an electron will be found in a certain range. Related to the wave function.
Term
Quality factor (QF)
Definition

aka Relative biological effectiveness (RBE)

aka Radiation weighting factor (wR)

The quantity that accounts for the difference in relative effect of radiation. Equal or greater than 1. A unitless multiplication factor.

Term
Quantum hypothesis
Definition
Radiation has properties of a wave during propagation and properties of a particle when emitted from atoms. It is both a wave and a particle.
Term
Quantum number
Definition

Specifies the number of electron half-wavelengths that appear in a box.

1, 2, 3, ...

Term
Quantum physics
Definition
The interaction of EM waves with atoms and molecules.
Term
Rad
Definition

1 rad = 0.01 J/kg

A unit dose is measured in.

Term
Radian
Definition
A unitless measure of an angle. One radian occurs when the arc of a section of a circle is equal to the radius of the circle.
Term
Radioactive emissions
Definition
Includes alpha, beta, and gamma.
Term
Radioactive series
Definition
A series of particles that nuclei turn into before reaching stability.
Term
Radio waves
Definition

λ > 10-3m

EM waves. Includes microwaves. Larger wavelengths are used for communications.

Term
Radius of curvature (r)
Definition
Positive when the direction from the centre of curvature of the surface is with the flow of light.
Term
Real image
Definition
When q is positive. Results when the rays from the object actually converge at the image. Can be seen as well as caught on a screen. Example: campera, projector, eye.
Term
Reduced eye model
Definition
The eye, assumed to be a single optical surface of variable power with air on one side and a uniform medium of 1.34 fluid on the other. Object distance is measured from 1.7 mm behind the surface of the eye.
Term
Reflect
Definition
Light bounces off a sufrace. Angle of incidience is the same as the angle of reflection.
Term
Refract
Definition
Light passes between two different transparent substances. The angle of incidence is not the same as the angle of refraction.
Term
Refractive index (n)
Definition
A constant for all transparent substances. Used in calculating the angle of refraction.
Term
Reissner's membrane
Definition
A membrane between the two chambers in the cochlea.
Term
Resistivity (ρ)
Definition
A property of a material. Measured in Ω•m.
Term
Resolved
Definition
Two diffraction patterns that can be distinguished.
Term
Resonance
Definition
Forced harmonic motion where the frequency is the same as the resonnce frequency. Easy to have a large amplitude.
Term
Resonance frequency
Definition
The frequency that an object oscillates at in SHM.
Term
Restoring force
Definition
The force that returns an object in SHM back to equilibrium position.
Term
Retina
Definition
A layer of photoreceptor cells, nerve cells, and nerve fibres at the back of the eye.
Term
Rhodopsin
Definition
A membrane protein found on the discs of rod photoreceptor cells. Made from the glycoprotein opsin.
Term
Rods
Definition
Rod-shaped photoreceptor cells in the retina. In the peripheral retina they respond best to yellow light and are responisble for scotopic vision. 1 μm in diameter at the base where it is photosensitive. Filled with folded phospholipid bilayer membrane discs. Rod is 25 μm long and has around 900 discs. Has visual pigment and rhodopsin on the membranes.
Term
Round window
Definition
A window in the cochlea that is flexible. Prevents damage from high pressures.
Term
Scalar
Definition
Quantity with magnitude and no direction. Example: time, temperature, speed.
Term
Scattering
Definition
The propagation direction is changed.
Term
Sclera
Definition
A white layer that surrounds the entire eyeball. The radius of curvature of a typical adult eyeball is 8.0 mm.
Term
Scotopic vision
Definition

aka Night-vision

Colour-blind. Cone and rod cells on the peripheral retina are responsible for scotopic vision.

Term
Second harmonic.
Definition

When there are two nodes.

For a double open-ended pipe, λ = length

For a stopped pipe, λ = ¾(length) 

Term
Section rule
Definition
When a chromophore absorbs light, an electron can only be elevated or de-elevated in n level by 1.
Term
Semiconductor
Definition
Materials with intermediate resistivity.
Term
Series
Definition
A circuit where the current lows through a number of resistors one by one.
Term
Singlet state
Definition
Electron spin does not change during electron transition.
Term
Simple harmonic motion (SHM)
Definition
When an object undergoes back-and-forth oscillating motion when displaced from equilibrium. Example: mass on a spring.
Term
Snellen Chart
Definition
A tool used by ophthlamologists to measure the acuity of pathients.
Term
Spectrophotometer
Definition
A device which measures the absorbance of sampels. Includes a light source, monochromator, sample chamber, and detector.
Term
Spherical waves
Definition
Waves that originate from a source and expand outwards in a sphere, like sound waves. The intensity is dependent on distance.
Term
Spin quantum number (s)
Definition
Tells the spin direction of an electron. Either +½, spin up (↑), or -½, spin down (↓).
Term
Standing wave
Definition

aka Stationary wave

When two waves of the same wavelength travel in opposite directions through the same medium. Often one wave is the reflection of the other.

Term
Stirrup
Definition
A bone in the middle ear. Vibrated by the eardrum.
Term
Stopped pipe
Definition
A pipe that is closed at one end, such as the pipes in a pipe organ. An antinode occurs at the open end.
Term
Stopping potential (Vs)
Definition
In the photoelectric effect, the absolute number of volts above which no more electrons are emitted, even when the intensity of light is increased. Depends on the type of metal and the frequency of light.
Term
Strings
Definition
The vibrating strings of  stringed musical instrument (violin, guitar, et cetera), are standing waves that have n number of nodes.
Term
Supercrest
Definition
A high ampliltude crest formed when there is constructive interference in a standing wave.
Term
Supertrough
Definition
A high amplitude trough formed when there is constructive interference in a standing wave.
Term
Tectorial membrane
Definition
A membrane between the two chambers in the cochlea. Protects the basilar membrane. The outer and inner hairs stimulate it in different regions for differen pithces, making neural signals.
Term
Thin lens equation
Definition
P = (1/p) + (1/q) = (1/f)
Term
Threshold frequency (f0)
Definition
In the photoelectric effect, the frequency of EM radiation below which no electrons are emitted, regardless of the intensity of radiation.
Term
Tissue weighting factor (wT)
Definition
Used in calculating effective dose.
Term
Transmittance
Definition
The amount of light absorbed by a substance.
Term
Transverse wave
Definition
A wave where the oscillation occurs perpendicular to the direction of travel. Example: a wave on the surface of water.
Term
Traveling wave
Definition
A disturbance which moves through space carrying energy without bulk forward movement of matter.
Term
Triplet state
Definition
When the electron flips spin number when excied. It now canno have vibrational relaxation. There is phosphorescence.
Term
Tritium
Definition

3H

A radioactive isotope of hydrogen found in trace quantities in water.

Term
Trough
Definition
A minimum point in a wave.
Term
Ultraviolet (UV) rays
Definition

10-9m < λ < 4 x 10-7m

Some of these waves are part of the solar spectrum. Can damage the external cells of the body.

Term
Unpolarised
Definition
When there is all possible polarisations of EM waves present. Most light is unpolarised.
Term
Unresolved
Definition
Two diffraction patterns that cannot be distinguished.
Term
Vector
Definition
Quantity with magnitude and direction. The magnitude is always positive. Example: force, velocity, acceleration, electric fields. Denoted by an arrow above the symbol.
Term
Velocity
Definition
Distance divided by time. Measured in meters per second.
Term
Vibrational relaxation
Definition
The transition to a lower vibrational state. Has fluorescence.
Term
Vibrational selection rule
Definition
Δv = ±1
Term
Virtual image
Definition
When q is negative. All light rays diverge in the image space, but seem to originate from the image. Can be seen but not caught on a screen. Example: mirror.
Term
Visible light
Definition

4 x 10-7 m < λ < 7.5 x 10-7 m

EM waves. A narrow region of the EM spectrum tha thas the correct wavelength to stimulate hte photochemical reactions in human vision.

Term
Visual axis
Definition

aka Optic axis

The normal of the eye. Extends through  the cornea to the geometric centre of the sphere. Hits the fovea.

Term
Visual pigment
Definition

aka Visual purple

A membrane protein found on the discs of a rod photoreceptor.

Term
Vitreous humor
Definition
A transparent fluid in the posterior chamber of the eye.
Term
Volt (V)
Definition

1 V = 1 J/C

A unit that measures electrical potential.

Term
Voltage differences (ΔV)
Definition
Electric potential difference. Measured experimentally. When the amount of work done while moving one Coloumb of charge from one point to another is exactly one J.
Term
Watt (W)
Definition
A unit that electrical power is measured in.
Term
Wave
Definition
An energy-carrying disturbance. Produces oscillations and vibrations. Matter does not move; only energy. Waves can be deflected and can interfere with each other.
Term
Wave function (Ψ)
Definition
Represents a wave. Related to probability density.
Term
Wave number (k)
Definition

aka Wave vector

2π/λ

Measured in m-1.

Term
Wavelength (λ)
Definition
The distance between two successive crests or troughs in a wave.
Term
Work function (Φ)
Definition
The minmum energy required to unbind an electron from a metal.
Term
X-rays
Definition

10-12 m < λ < 10-9 m

EM waves. Ionizing radaiton. Iportant for medical diagnosis.

Term
Zero point energy
Definition

Where E = ½hf

The loest energy level of a molecule.

Supporting users have an ad free experience!