A charge-coupled device (CCD) attached to a telescope measures the wavelength at…

PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A charge-coupled device (CCD) attached to a telescope measures the wavelength at which the radiated energy from a star has maximum intensity as

400\ \text{nm}

and the power received at the Earth's surface per unit area as

2.8 \times 10^{-10}\ \text{W m}^{-2}

. (a) Show that the surface temperature of the star is about

7300\ \text{K}

. (b) At this temperature, the total power emitted by the star is determined to be

7.2 \times 10^{27}\ \text{W}

. Calculate how far away the star is from the Earth. Give your answer in standard form and in light-years.