Astronomy 100 -- Worksheet #9
Properties of LIGHT
1) Light behaves like both a _____________ and a _____________.
2) The distance between adjacent crests of a light wave is called the _____________ of the light.
3) The number of light waves which pass you per second is known as the _____________ of the light.
4) The distribution of light according to wavelength is known as the _____________.
5) A particle of light is known as a(n) _____________. These _____________ have no _____________
and they travel with a velocity called the ____________________.
6) The energy of a photon is greater if its _____________ is greater.
7) The seven wavelength regions of the electromagnetic spectrum, ordered in terms of increasing
wavelength, are _____________, _____________, _____________, _____________, _____________,
_____________, and _____________. The highest energy photons are the _____________ photons.
Among optical photons, the shorter wavelengths appear _____________ in color, while the longer
wavelengths appear _____________ in color.
8) The Inverse Square Law of light states that the brightness of an object decreases as the
________________________________. If a car is approaching you as you watch in the rear-view mirror,
when it has moved 6 times closer to you, the headlights will appear ____________ times
_____________(brighter/fainter).
9) The fact that light bends when it travels from one medium to a medium of different density is known
as _____________.
10) The fact that shorter wavelengths are bent more than longer wavelengths is known as
_____________. This property leads to the formation of _____________ when sunlight interacts with
raindrops.
11) The study of the spectra of astronomical objects is known as _____________.
12) The laws which describe the types of spectra produced under different physical conditions are known
as _____________’s Laws. The type of spectrum produced by a hot solid or a hot dense gas is called a(n)
_____________________ spectrum.
13) The type of spectrum produced by a hot diffuse gas is called a(n) _____________ spectrum.
14) The type of spectrum produced by a cool gas in front of a hot continuous spectrum is called a(n)
_____________________ spectrum.
15) The type of spectrum produced by most stars is called a(n) _____________________ spectrum, be-
-2cause most stars resemble a _____________ in front of a ____________________.
16) The apparent change in the wavelength of light or sound, due to relative motion between a source and
observer, is known as the _____________ effect.
17) The fact that different chemical elements exhibit distinct patterns of spectral lines is due to the structure of the _____________.
18) In an atom, the _____________ orbit the nucleus in distinct energy levels. The particles called
_____________ and _____________ are contained in the nucleus and constitute most of the
_____________ of the atom.
19) In an atom, when an electron changes energy levels, a _____________ line is produced.
20) When an electron jumps to a higher energy level, a(n) __________________ is produced. When an
electron jumps to a lower energy level, a(n) __________________ is produced.
21) Every atom with a given mass and charge produces spectral lines of certain unique _____________
because the spacing of the energy levels is unique to an atom of that mass and charge.
22) The continuous radiation, or continuous spectrum of emission, produced by every object by virtue of
its temperature is known as _____________ radiation.
23) An object at any temperature emits some energy at all _____________. A hotter object emits more
energy per square centimeter at all _____________ than does a cooler object. A hotter object also emits
most of its energy at _____________ (shorter/longer) wavelengths.
24) The color a star appears to have will depend on its temperature. A hot star emits most of its energy at
_____________ wavelengths, and since these wavelengths in the optical region appear to be
_____________ in color, a hot star will appear _____________. Conversely, a cool star emits most of its
energy at _____________ wavelengths, and since these wavelengths in the optical region appear to be
_____________ in color, a cool star will appear _____________.
25) The total energy emitted by a star depends on both its _____________ and its _____________.