$[1/2$ Points$]$

SERCP$1221\mathrm{.}11.$P$\mathrm{.}058.$

PRACTICE ANOTHER

Consider a bright star in our night sky$.$ Assume its distance from Earth is $80\mathrm{.}6$ light$-$years $($Iy$)$ and its power output is $4\mathrm{.}00{10}^{28}W,$ about $100$ times that of the Sun. One light$-$year is the distance traveled by light through a vacuum in one year.

$($a$)$ Find the intensity of the starlight at the Earth.

$\frac{w}{m^2}$

$($b$)$ Find the power of the starlight the Earth intercepts. $($The radius of Earth is $6\mathrm{.}38{10}^{6}m.)$

Your response differs significantly from the correct answer. Rework your solution frory the beginning and check each step carefully. MW

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$9.[1/2$ Points$]$

SERCP$1221\mathrm{.}12.$P$\mathrm{.}059.$

What are the wavelengths of electromagnetic wave in free space that have the following frequencies?

$($a$)3\mathrm{.}00{10}^{19}Hz$

$pm$

$($b$)2\mathrm{.}50{10}^{9}Hz$

Your response is off by a multiple of ten. cm