25.1 Standard candles

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.