Question

which of the following can be used to determine the temperature of a star?
a) the stars magnetic field
b) line spectra
c) light from sunspots
d) blackbody spectrum
question 10 (5 points)
which of the terrestrial planets is the largest?
a) mars
b) earth
c) mercury
d) venus

Explanation:

• For the first question:
• The blackbody spectrum is related to the temperature of an object. Stars can be approximated as blackbodies, and by analyzing their blackbody spectrum (using Wien's law, which relates the peak wavelength of the spectrum to the temperature \(T=\frac{b}{\lambda_{max}}\), where \(b = 2.898\times10^{-3}\text{m}\cdot\text{K}\) is Wien's displacement constant), we can determine the star's temperature.
• A star's magnetic field is related to its internal dynamics (like dynamo effects) and not directly to its temperature.
• Line spectra are used to determine the chemical composition of a star (by comparing the observed spectral lines with known atomic/molecular spectra), not its temperature.
• Light from sunspots is cooler than the average photosphere of the Sun (a type of star), but analyzing sunspot light alone is not a general - purpose method for determining a star's temperature.
• For the second question:
• Terrestrial planets are Mercury, Venus, Earth, and Mars.
• The radii of these planets (approximate values): Mercury (\(r\approx 2440\text{ km}\)), Venus (\(r\approx 6052\text{ km}\)), Earth (\(r\approx 6371\text{ km}\)), Mars (\(r\approx 3390\text{ km}\)). By comparing their sizes (using radius as a measure of size for spherical - like planets), Earth is the largest among the terrestrial planets.

Answer:

• First question: D) Blackbody spectrum
• Second question: B) Earth