Physics 9702 · AS & A Level · Stellar radii

Stellar radii — practice question

(a)[1]

State what luminosity of a star means.

(b)[2]

The Sun has luminosity $3.83 \times 10^{26}\,\text{W}$. The Earth-Sun distance is $1.51 \times 10^{11}\,\text{m}$. Calculate the radiant flux intensity $F$ of the Sun at the Earth. Include a unit in your answer.

(c)[1]

Use the data from (b) to determine the mass converted into energy each second in the Sun.

(d)[1]

The radius of the Sun is $6.96 \times 10^{8}\,\text{m}$. Show that the surface temperature $T$ of the Sun is $5770\,\text{K}$.

(e)[2]

The wavelength $\lambda_{\max}$ of light for which the greatest rate of emission occurs from the Sun is $5.00 \times 10^{-7}\,\text{m}$. The surface temperature of the star Sirius is $9940\,\text{K}$. Use information from (d) to find the wavelength of light for which the greatest rate of emission occurs from Sirius.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Total power emitted by the star

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI