Astronomy Exam Practice Quiz Questions

The relationship between wavelength, frequency, and energy for photons of light is described by the equation E = hf, where E is the energy of the photon, h is Planck's constant, and f is the frequency of the photon. As frequency is directly proportional to energy, an increase in frequency results in an increase in energy. On the other hand, wavelength and frequency are inversely related, meaning that as wavelength increases, frequency decreases. Therefore, longer wavelength corresponds to lower frequency and lower energy.

According to the Planck's law of black body radiation, the energy of a photon is directly proportional to its frequency (or inversely proportional to its wavelength). As temperature increases, the average energy of photons emitted by a hot object also increases. Therefore, a hot object emits photons with a higher average energy than a cool object.

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The correct answer is that the spectral lines of most galaxies show redshifts, which means that their wavelengths are longer than normal. This phenomenon occurs because of the Doppler effect, where the light waves from these galaxies are stretched as the galaxies move away from us. As a result, the wavelengths of the spectral lines are shifted towards the red end of the spectrum. This redshift is a key piece of evidence for the expansion of the universe.

Low-mass stars are cooler and less luminous than high-mass stars because their lower mass results in less gravitational pressure and lower temperatures. They also have less fuel to burn, leading to lower luminosity compared to high-mass stars.

The temperature of the core of the Sun is estimated to be around 10 million K. This high temperature is necessary for the nuclear fusion reactions that occur in the core, where hydrogen atoms combine to form helium, releasing large amounts of energy. This temperature is much higher than any of the other options provided, making 10 million K the closest value.

The correct answer is 100 parsecs. Stellar parallax is a method used to measure the distance to nearby stars by observing their apparent shift in position against the background of more distant stars as the Earth orbits the Sun. The accuracy of this method decreases with increasing distance, and the maximum distance at which we can measure stellar parallax is approximately 100 parsecs. Beyond this distance, the shift in position becomes too small to accurately measure.

Neutrinos are difficult to detect because they rarely interact with matter. Unlike other particles, neutrinos have a very weak interaction with matter, making it extremely challenging to detect them. They can pass through large distances of material without any interaction, making them elusive to detect. This property of neutrinos makes them ideal for studying astrophysical phenomena, such as supernovae, as they can travel through space without being significantly affected by other particles.