Astronomy 263 Chp 5 Purdue

Red light comes from the transition from E3 to E2. These photons will have the _____ wavelengths because they have the ______ energy. a. shortest; least b. shortest; most c. longest; least d. longest; most

Photons with shorter wavelength have greater energies but not least energies ANSWER C LONGEST; LEAST

T/F Cooler objects radiate more of their total light at shorter wavelengths than do hotter objects.

Hotter objects emit photons with shorter wavelengths. since, particles inside a hot object move more energetically, they emit photons with high energy. High energy photons have short wavelengths. But, cooler objects radiate light at longer wavelengths. ANSWER FALSE

Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare? a. Star A is 4 times as luminous as Star B b. Star A is 2 times as luminous as Star B c. Star B is 2 times as luminous as Star A d. star B is 4 times as luminous as Star A

ANSWER A STAR A IS 4 TIMES AS LUMINOUS AS STAR B

Suppose you have a block of material in which half the atoms decay in 2 minutes. After 6 minutes, what fraction of the original material remains? a. 1/2 b. 1/4 c. 1/6 d. 1/8 e. 1/64

ANSWER D 1/8

what is the surface temperature of a star that has a peak wavelength of 290 nm? a. 1,000 K b. 2,000 K c. 5,000 K d. 10,000 K e. 100,000 K

ANSWER D THE SURFACE TEMPERATURE OF THE SUN IS 10,000 K

when a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of a. the bohr model b. the heisenberg uncertainty principle c. emission and absorption d. the doppler effect

ANSWER D bohr's model- protons and neurons heisenberg's uncertainty principle- deals with the impossibility in knowing the position and momentum of a particle exactly at the time emission and absorption- electrons jump from higher energy levels to lower energy levels they emit photons (emission), absoroption means absorbing a photon THE DOPPLER EFFECT: the change in wavelength of sound or light that is due to the relative motion of the source toward or away from the observer

T/F an atom can emit or absorb a photon of any wavelength

Atoms cannot absorb or emit photons of any wavelength. The wavelengths of the photons emitted by an atom or absorbed by an atom are determined by the difference between the two energy levels. ANSWER FALSE

T/F The frequency of a photon is related to the energy of the photon

E=hf E= energy of a photon, h= Planck's constant, f=frequency of the photon ANSWER TRUE

T/F The emission spectrum of a helium atom is identical to that of a carbon atom.

Emission spectrum of each element is different. ANSWER FALSE

two stars are of equal luminosity. Star A is 3 times as far from you as star B. Star A appears _________ star B. a. 9 times brighter than b. 3 times brighter than c. the same brightness as d. 1/3 as bright as e. 1/9 as bright as

Star A's brightness is inversely proportional to the square of the distance from star B. So, Star A appears 1/9 as bright as star B, but not 1/3 as bright as star B. ANSWER E 1/9 STAR A APPEARS 1/9 AS BRIGHT AS STAR B

Suppose an atom has three energy levels, specified in arbitrary units as 10, 7, and 5. In these units, which of the following energies might an emitted photon have? a. 3 b. 2 c. 5 d. 4

The emitted photon doesn't have the energy unit of 4. ANSWER A3, B2 AND C5

as a blackbody becomes hotter, it also becomes______ and _______. a. more luminous, redder b. more luminous, bluer c. less luminous, redder d. less luminous, bluer

The luminosity of a black body increases with temperature. Hot bodies emit photons with shorter wavelengths. Blue light has shorter wavelengths, so they appear blue. ANSWER B MORE LUMINOUS, BLUER

How does the speed of light in a medium compare the speed in a vacuum? a. It's the same, since the speed of light is a constant. b. the speed in the medium is always faster than the speed in a vacuum. c. the speed in the medium is always slower than the speed in a vacuum. d. the speed in the medium may be faster or slower, depending on the medium.

The speed of light is always faster in a vacuum ANSWER C the speed in the medium is always slower than the speed in a vacuum.

the temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms a. are very large b. are moving very fast c. are all moving together d. are very massive e. have a lot of energy

When the temp increases, the atoms move faster and create more energy. ANSWER B ARE MOVING VERY FAST AND ANSWER E HAVE A LOT OF ENERGY

light acts like

a wave and a particle

Why is an iron atom a different element from a sodium atom?

an iron atom has more protons in its nucleus than a sodium atom has, but not because of the bigger size of sodium atoms.

which of the following factors does not directly influence the temperature of a planet? a. the luminosity of the sun b. the distance from the planet to the sun c. the albedo of the planet d. the size of the planet

energy=luminosity= temperature closer the planet to the sun, hotter the temp as the planet's albedo increases, it reflects more and the temperature of the planet decreases. ANSWER D THE SIZE OF THE PLANET

T/F blue light has more energy than red light

higher frequency photons carry more energy. the frequency of blue light is higher than red light. so, blue light has more energy than red light. ANSWER TRUE

If a planet is in thermal equilibrium, a. no energy is leaving the planet b. no energy is arriving on the planet c. the amount of energy leaving equals the amount of energy arriving d. the temperature is very low

in thermal equilibrium, energy leaves the planet. This amount must be equal to the amount of energy arriving on the planet. ANSWER C THE AMOUNT OF ENERGY LEAVING EQUALS THE AMOUNT OF ENERGY ARRIVING

ranking the following in order of decreasing wavelength a. gamma rays b. visible light c. infared light d. ultraviolet light e. radio waves

radio waves (longer than 1 mm) infrared light (longer than 750 nm and shorter than 500 um) visible light (between 750 nm and 380 nm) ultraviolet light (between 40 nm and 380 nm) gamma rays (less than about 10^-6 m)

When an electron moves from a higher energy level in an atom to a lower energy level a. the atom is ionized b. a continuous spectrum is emitted c. a photon is emitted d. a photon is absorbed

the atom is not ionized when an electron moves from a higher energy level to a lower energy level. But, a photon is emitted. A photon is emitted, but not absorbed, when an electron jumps from a higher energy level to a lower energy level of an atom. ANSWER C A PHOTON IS EMITTED

Suppose you have two monochromatic light beams. Beam 1 has half the wavelength of beam 2. How do their frequencies compare? a. beam 1 has 4 time the frequency of beam 2 b. beam 1 has 2 times the frequency of beam 2 c. they are the same d. beam 1 has 1/2 the frequency of beam 2 e. beam 1 has 1/4 the frequency of beam 2

the frequency of beam 1 is 2 times larger than the frequency of beam 2, but not 4 time larger ANSWER B beam 1 has 2 times the frequency of beam 2

at what wavelength does your body radiate the most energy? (Assume that your temperature is approximately that of Earth, which is 300 K) a. 10^-5 meter b. 10^-3 meter c. mass and energy d. mass and velocity e. mass and acceleration

the peak wavelength is 10^-5 m ANSWER A 10^-5 meter

Momentum is the product of a. mass and position b. position and energy c. mass and energy d. mass and velocity e. mass and acceleration

the product of mass and acceleration is force, but not momentum. ANSWER D mass and velocity

when less energy is radiated from a terrestrial planet, its _______ increases until a new __________ is achieved. a. temperature; equilibrium b. size; temperature c. equilibrium; size d. temperature; size

the size of the planet doesn't increase to achieve a new temperature. But, temperature will increases until a new equilibrium is achieved. ANSWER A TEMPERATURE INCREASES UNTIL A NEW EQUILIBRIUM IS ACHIEVED