The fractional change in the wavelength of the observed light from a galaxy is 0.15; its redshift is 15%.

Calculate its recession speed. State any assumptions made.

The Tadpole galaxy has a recession speed of $9400 \mathrm{km} {\mathrm{s}}^{-1}$.

Calculate the fractional change in the wavelength of the observed spectrum.

Which statement is correct about radiant flux intensity?

(A) It depends on the area of the measuring device.

(B) It is measured in ${\mathrm{Wm}}^{-2}$.

(C) It is the same as luminosity.

(D) It is the total radiant power emitted from a star.

A group of astronomers have determined the radiant flux intensity F from a star and its distance d. The percentage uncertainty in F is $1.2\%$ and the percentage uncertainty in d is $2.5\%$. What is the percentage uncertainty in the calculated value of the luminosity of the star?

A particular emission spectral line is measured in the laboratory to have a frequency of $7.3\times {10}^{14} \mathrm{Hz}$. Calculate the wavelength of this spectral line in the laboratory.

A particular emission spectral line is measured in the laboratory to have a frequency of $7.3\times {10}^{14} \mathrm{Hz}$.

(b) Calculate the observed wavelength of this same spectral line in the spectrum of a galaxy moving away from the Earth at a speed of:

(i) $11{\mathrm{Mms}}^{-1}$

A particular emission spectral line is measured in the laboratory to have a frequency of $7.3\times {10}^{14} \mathrm{Hz}$. Calculate the observed wavelength of this same spectral line in the spectrum of a galaxy moving away from the Earth at a speed of $7.0\%$ the speed of light.