Astronomy Chapter 3

As they move through space, the vibrating electrical and magnetic fields of a light wave must move perpendicular to each other.

True

There are no X-ray telescopes on Earth because

X-rays don’t penetrate Earth’s atmosphere

Gamma Rays are a type of electromagnetic radiation.

True

Star A has a temperature 1/2 that of star B, but star A is 5 times bigger than star B. Which statement below is correct?

Star A is redder and brighter than star B.

The light from an object moving tangentially (to your left or right) will exhibit

no shift.

While gravity is always attractive, electromagnetic forces are always repulsive.

False

Of all the forms of electromagnetic radiation, the one with the lowest frequency is

radio waves

A wave’s velocity is the product of the

frequency times the wavelength of the wave

At which of these Kelvin temperatures would a blackbody radiate mostly at visible wavelengths?

6000 K

Which of these is constant for ALL types of electromagnetic radiation in a vacuum?

Velocity

The frequency of a water wave gives us its height.

False

If a new wave arrives on shore every two seconds, then its frequency is 2 Hz.

False

Increasing the temperature of a blackbody by a factor of 3 will increase its energy by a factor of

81

The visible color of electromagnetic radiation that has the shortest wavelength is

violet

Radio waves, visible light, and X-rays are all a type of electromagnetic radiation.

True

The Doppler Effect is a phenomenon that allows one to measure an object’s

radial motion

X-rays travel at a greater speed than radio waves.

False

You would perceive a change in a visible light wave’s amplitude as a change in its color.

False

A blue star has a higher surface temperature than a red star.

True

Stars like our Sun emit most of their light in which part of the electromagnetic spectrum?

the visible

According to Wein’s Law, if the surface temperature is increased by a factor of 2, its peak wavelength will

decrease by a factor of 2

The two forms of electromagnetic radiation that penetrate the atmosphere best are:

visible and radio waves.

Which type of radiation can be observed well from Earth’s surface?

visible

If a wave’s frequency doubles, its wavelength

is halved.

Observations in the X-ray portion of the spectrum are routinely done from the surface of the earth.

False

The hottest objects with temperatures in the millions of degrees Kelvin, give off most of their radiation in which part of the electromagnetic spectrum?

X-ray

Stefan’s Law says:

that if the Sun’s temperature were doubled, it would give off 16X more energy.

If a light source is approaching you at a speed very close to the speed of light, it will appear

bluer than it is

Wein’s law relates the peak wavelength of the blackbody to its size. The larger the black body, the shorter its peak wavelength

False

As the Sun evolves into a red giant in the distant future, then according to Wien’s Law:

its peak on the Planck curve will move into the infrared.

Changing the electric field will have no effect on the magnetic fields of a body.

False

Doubling the temperature of a black body will double the total energy it radiates

False

As white light passes through a prism, the red (longer) wavelengths bend less than the blue (shorter) wavelengths, so forming the rainbow of colors.

True

Electromagnetic radiation with a wavelength of 700 nm would be:

red light

Wave energy can only be transmitted through a material medium.

False

An observer will measure the wavelength of waves emanating from a source that is moving away as longer than it really is.

True

Very low temperature molecular clouds emit most of their light in which part of the electromagnetic spectrum?

The radio

The greater the disturbance of the medium, the higher the amplitude of the wave.

True

The temperature scale that places zero at the point where all atomic and molecular motion ceases is

Kelvin

The wavelength at which a blackbody radiates most depends on its

Temperature

The total energy radiated by a blackbody depends on

the fourth power of its temperature

X-ray telescopes are located in orbit around the Earth because

X-rays don’t reach the surface of Earth

According to Wein’s law, the higher the surface temperature of a star, the redder its color.

False

As a star’s temperature increases, the frequency of peak emission also increases.

True

In blackbody radiation, the energy is radiated uniformly in every region of the spectrum, so the radiating body appears black in color.

False

There are no radio telescopes in space because

radio waves penetrate Earth’s atmosphere so there is no need to put one in space

The number of waves passing the observer per second is:

the frequency in Hertz