Science 30 Unit C
refraction
a bending in the direction of a wave that occurs when the wave changes speed
Doppler effect
a change in the observed frequency of a wave due to motion between the source and the observer
white dwarf
a compact star found as the last stage in the evolution of low-mass stars
red shift
a decrease in frequency due to a source of EMR moving away from an observer, due to the Doppler effect
transformer
a device that transforms the AC voltage of one circuit into a different AC voltage for another circuit using separate solid of wire wound around a common iron core
direct current (DC)
a flow of charges that does not increase or decrease and flows in a single current
alternating current (AC)
a flow of charges that reverses directions at regular intervals
very large array
a group of radio telescopes distributed over many kilometres along the arms of a Y-shapes track
constellation
a group of stars perceived as being in the shape of a figure or a design
insulator
a material in which none of the electrons can move freely, preventing the material from being able to conduct an electric current
conductor
a material in which some of the electrons can move freely, allowing the material to conduct an electric current
magnetic resonance imaging (MRI)
a method of obtaining internal images of objects, especially living organisms, by using radio waves and strong magnetic fields
commutator
a part of a motor or generator found on the armature that provides electrical contact, allowing current to flow to the rotating coil
shaft
a part of a motor or generator that supports the coil of the armature, providing an axis for the rotation of the armature
diffraction pattern
a pattern produced by waves that have undergone diffraction
diffraction grating
a piece of glass or plastic with thousands of tightly spaced lines etched on its surface; used to produce spectra
nuclear fusion
a process in which two smaller nuclei join to form a larger nucleus, releasing energy
magnetic field
a property of the space around a magnet or an electric current that enables the magnet or electric current to exert forces on other magnets such as compass needles, and electric currents that enter this region
gravitational field
a property of the space around a source mass that enables the source mass to exert forces on other masses that enter this region
electric field
a property of the space around a source that enables the source charge to exert forces on other charges that enter this region
reflection
a return of a wave from a boundary
pulsar
a rotating neutron star that emts radiation in regular pulses
series connection
a single path available for electric current where the charges flow through one device before passing through to the next
schematic diagram
a sketch that uses symbols to detail the components of a system such as an electrical circuit (pg374)
photon
a small bundle of electromagnetic energy
continuous spectrum
a spectrum having no distinct lines that is distributed over an unbroken band of wavelengths
absorption spectrum or dark-line spectrum
a spectrum that has a pattern of dark lines due to the light passing through a absorbing medium; can be used to identify a material
emission spectrum or bright-line spectrum
a spectrum that has a pattern of separate bright lines that is emitted from an excited gas under low pressure; can be used to identify a material
red giant
a star of great size and age that has a relatively low surface temperature
brush
a stationary part of a motor or generator that makes electrical contact with the rotating commutator
supernova
a stellar explosion that produces a very bright cloud of ionized gas that remains a very bright object in the sky for weeks or months
cosmic rays
a stream of high-speed, ionized particles ejected from the objects beyond the solar system, consisting mainly of atomic nuclei
solar wind
a stream of high-speed, ionized particles ejected from the sun, consisting mainly of electrons, protons and helium nuclei
neutron star
a super-dense star consisting mainly of neutrons formed as the last stage in the stellar evolution of intermediate-mass stars
radioactive
a term used to describe substances that spontaneously emit radiation from unstable nuclei
antenna
a transmitter or receiver of electromagnetic energy
ultraviolet light, ultraviolet radiation or UV
a type of electromagnetic radiation that is emitted by very hot objects; frequencies range from 7.5×10¹⁴ to 1×10¹⁸
microwaves
a type of electromagnetic radiation with a frequency between 1 GHz and 100 GHz; used for radar, satellite communications and cooking food
radio wave
a type of electromagnetic radiation with a frequency less than 3000 GHz; used primarily for communications
infrared light or infrared radiation
a type of electromagnetic radiation, with s frequency between 3.0×10¹¹ Hz and 4.3×10¹⁴ Hz, that increases the vibrations between molecules, resulting in heating effects
transverse wave
a wave in which the vibrations are perpendicular to the direction the wave is travelling
electromagnetic radiation (EMR)
a wave that consists of a changing electric field and a changing magnetic field travelling at right angles to one another
coulomb
an SI unit for charge; one coulomb is equivalent to the transfer of 6.25×10¹⁸ electrons
black hole
an area in space with a gravitational field so strong that neither matter nor EMR can escape; formed as the last stage in the evolution of high-mass stars
resistor
an electronic component that resists the flow of electric current in a circuit
false-colour image
an image that depicts an object in colours that differ from how a person would see the same object using only his or her eyes; often used to produce images using EMR outside of the visible spectrum
blue shift
an increase in frequency due to a source of EMR moving toward an observer, due to the Doppler effect
ohmmeter
an instrument that measures the resistance across two points in a circuit
ammeter
an instrument that measures the voltage across two points in a circuit
voltmeter
an instrument that measures the voltage across two points in a circuit
nebula
an interstellar cloud of gas and dust
test body
an observable abject that can experience a force due to the presence of a field
spectrometer
an optical instrument that is sued to measure the wavelengths of light
voltage
another term for electric potential difference
polarization
confining a wave to vibrate in one direction
grounded
connected to the ground; providing a safe conducting path for stray or excess charges; having zero electric potential energy
extremely low frequency (ELF)
electromagnetic radiation with a frequency between 3 and 300 Hz; emitted from power distribution cables
radiation
energy emitted in the form of particles or waves
positively charged
having fewer electrons than protons creating an imbalance
negatively charged
having more electrons than protons creating an imbalance
X-rays
high energy electromagnetic radiation with a frequency between 10¹⁸ and 10²¹ Hz; can be produced when fast-moving electrons strike a metal target
ionizing radiation
high-energy radiation capable of ionizing the material through which it passes, leading to the formation of free radicals
field lines
lines that describe the direction of a field by the way they point, and the strength of a field by their density
parallel connection
more than one path available for electric current, where the electric current divides, allowing each portion of the current to simultaneous pass through separate devices
cycle
one complete vibration of a wave
spectra
plural form of spectrum
resolution
the amount of small detail visible in an image; low resolution means only large features can be seen, while high resolution means that small details can be seen
diffraction
the bending of a wave as it passes by obstacles or by the edges of an opening
electric potential difference
the change in potential energy per unit of charge
secondary coil
the coil that supplies the output voltage of a transformer
primary coil
the coil to which the input voltage is applied in a transformer
beaming
the communication of data between wireless devices using a beam of infrared light
visible spectrum
the complete range of all colours of light that can be seen by the human eye; red, orange, yellow, green, blue, indigo and violet; frequencies range from 4.3×10¹⁴ Hz to 7.5×10¹⁴ Hz
wavelength
the distance from a point on one wave to the corresponding point on the next wave; the length of one cycle
electrical energy
the energy made available by the movement of charge
mechanical energy
the energy possessed by an observable object due to motion or its position; the sum of the kinetic energy and potential energy of an object
electric current
the flow of electric charge from one point to another
electric force
the force exerted on a charged test body by an electric field; calculated by ,multiplying the electric field strength by the charge on the test body
gravitational force
the force exerted on a test body by a gravitational field; calculated by multiplying the mass of the test body by the gravitational field strength
gamma radiation
the highest energy form of electromagnetic radiation with frequencies above 10¹⁹Hz; emitted from the nuclei of radioactive materials
radiation therapy
the medical use of ionizing radiation to treat disease, especially forms of cancer
frequency
the number of cycles per second
electric field strength
the number of newtons per coulomb that a test body will experience at a given location from a source charge
gravitational field strength
the number of newtons per kilogram a test body will experience at a given location from a source mass
power
the rate of doing work or transforming energy
resistance
the ratio of the voltage across a device to the current flowing through it
astronomy
the science of objects and phenomena that originate outside earth's atmosphere
armature
the section of a motor or generator that rotates, consisting of a coil of wire, rotating shaft, and a commutator (pg 359)
multi wavelength astronomy
the study of objects in space using the principle that these objects reveal different aspects of their behaviours through the many wavelengths of EMR they emit
kilowatt-hour
the traditional unit for electrical energy used by utility companies; 1 kWh=3.6MJ
volt
the unit for electric potential difference 1V= 1J/C
hertz (Hz)
the unit for frequency
electromagnetic spectrum
the wide band of different types of electromagnetic radiation ranging from radio waves to gamma rays
