25. Astronomy and cosmology

understand the term luminosity as the total power of radiation emitted by a star.

Use —the term luminosity as the total power of radiation emitted by a star to connect the rule to the data and decision in the question.

This matters because —the term luminosity as the total power of radiation emitted by a star determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the term luminosity as the total power of radiation emitted by a star to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The term luminosity as the total power of radiation emitted by a star is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

recall and use the inverse square law for radiant flux intensity F in terms of the luminosity L of the source F = L / (4πd 2).

Use —the inverse square law for radiant flux intensity f to connect the rule to the data and decision in the question.

This matters because —the inverse square law for radiant flux intensity f determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the inverse square law for radiant flux intensity f to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The inverse square law for radiant flux intensity F is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

understand that an object of known luminosity is called a standard candle.

Use —an object of known luminosity is called a standard candle to connect the rule to the data and decision in the question.

This matters because —an object of known luminosity is called a standard candle determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —an object of known luminosity is called a standard candle to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —An object of known luminosity is called a standard candle is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

understand the use of standard candles to determine distances to galaxies.

Use —the use of standard candles to determine distances to galaxies to connect the rule to the data and decision in the question.

This matters because —the use of standard candles to determine distances to galaxies determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the use of standard candles to determine distances to galaxies to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The use of standard candles to determine distances to galaxies is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

recall and use Wien’s displacement law λmax ∝ 1 / T to estimate the peak surface temperature of a star.

Use —wien’s displacement law λmax ∝ 1 / t to estimate the peak surface to connect the rule to the data and decision in the question.

This matters because —wien’s displacement law λmax ∝ 1 / t to estimate the peak surface determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —wien’s displacement law λmax ∝ 1 / t to estimate the peak surface to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Wien’s displacement law λmax ∝ 1 / T to estimate the peak surface is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

use the Stefan–Boltzmann law L = 4 πσr 2 T 4.

Use —the stefan–boltzmann law l = 4 πσr 2 t 4 to connect the rule to the data and decision in the question.

This matters because —the stefan–boltzmann law l = 4 πσr 2 t 4 determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the stefan–boltzmann law l = 4 πσr 2 t 4 to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The Stefan–Boltzmann law L = 4 πσr 2 T 4 is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

use Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius of a star.

Use —wien’s displacement law and the stefan–boltzmann law to estimate the radius to connect the rule to the data and decision in the question.

This matters because —wien’s displacement law and the stefan–boltzmann law to estimate the radius determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —wien’s displacement law and the stefan–boltzmann law to estimate the radius to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

understand that the lines in the emission and absorption spectra from distant objects show an increase in wavelength from their known values.

Use —the lines in the emission and absorption spectra to connect the rule to the data and decision in the question.

This matters because —the lines in the emission and absorption spectra determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the lines in the emission and absorption spectra to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The lines in the emission and absorption spectra is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

use ∆λ / λ ≈ ∆f / f ≈ v / c for the redshift of electromagnetic radiation from a source moving relative to an observer.

Use —redshift of electromagnetic radiation to connect the rule to the data and decision in the question.

This matters because —redshift of electromagnetic radiation determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —redshift of electromagnetic radiation to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Redshift of electromagnetic radiation is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

explain why redshift leads to the idea that the universe is expanding.

Use —why redshift leads to the idea that the universe is expanding to connect the rule to the data and decision in the question.

This matters because —why redshift leads to the idea that the universe is expanding determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —why redshift leads to the idea that the universe is expanding to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Why redshift leads to the idea that the universe is expanding is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

recall and use Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units).

Use —hubble’s law v ≈ h0d and explain how this leads to the big bang theory to connect the rule to the data and decision in the question.

This matters because —hubble’s law v ≈ h0d and explain how this leads to the big bang theory determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —hubble’s law v ≈ h0d and explain how this leads to the big bang theory to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.