OCR Specifications

 Module P1: The Earth in the Universe

P1.3 What is known about stars and galaxies?

10. recall that distant galaxies are moving away from us;

11. relate the distance of galaxies to the speed at which they are moving away; (Hubble’s law, but not redshift);

12. understand why the motions of galaxies suggests that Space itself is expanding;

Module P6: The wave model of radiation<

P6.3 Do all types of electromagnetic radiation behave in the same way?

1. recall that the different colours of light in the spectrum have different frequencies (and therefore wavelengths);

2. list the parts of the whole electromagnetic spectrum in order of frequency
or wavelength (radio waves, microwave, infrared , visible light, ultraviolet,
X-rays, gamma radiation);

3. recall that the energy delivered by each photon in a beam of
electromagnetic radiation increases with the frequency of the electromagnetic waves;

4. understand that the intensity of a beam of electromagnetic radiation (the
energy it delivers per second) depends on the number of photons arriving
every second and the amount of energy carried by each photon;

5. know that all types of electromagnetic radiation travel at exactly the
same, very high, speed through space (a vacuum), 300,000 km/s;

Module P7: Further Physics observing the Universe
P7.3 What are the objects we see in the night sky and how far away are they?

10. recall that Cepheid variable stars pulse in brightness, with a period related to their brightness;

11. explain qualitatively how this relationship enables astronomers to estimate the distance to Cepheid variable stars;

12. understand the role of observations of Cepheid variable stars in establishing  the scale of the Universe and the nature of most nebulas as distant galaxies (IaS 1.3, 1, 4);

13. recall that telescopes revealed that the Milky Way consists of very many stars and led to the realisation that the Sun was a star in the Milky Way galaxy;

14. recall that telescopes revealed the existence of many fuzzy objects in the
night sky, and that these were originally called nebulae;

15. recall the main issue in the Curtis-Shapley debate: whether nebulae were
objects within the Milky Way or separate galaxies outside it;

16. recall that Hubble’s observations of Cepheid variables in one nebula
indicated that it was much further away than any star in the Milky Way, and
hence that this nebula was a separate galaxy;

17. recall that intergalactic distances are typically measured in megaparsecs
(Mpc);

18. recall that Cepheid variable data in distant galaxies has given accurate
values of the Hubble constant;

19. use the following equation to calculate, given appropriate data, the speed of
recession, the Hubble constant and the distance to distant galaxies:

 speed of recession (km/s)=

Hubble constant (s-1 or km/s per Mpc) × distance  (km or Mpc)
 
 

Waves and EM spectrum<

 Hubble's Law

The Great Debate

Finding distances

 Module P2: Living for the Future

Item P2h: The Big Bang

Assessible learning outcomes Foundation tier only:low demand
Describe some ideas about the Big Bang theory for
the origin of the Universe;
• started with an explosion;
• the Universe is still expanding.

 Assessable learning outcomes both tiers:  standard demand

 Describe that:
• all galaxies are moving away from us;
• distant galaxies are moving away more quickly;
• microwave radiation is received from all
parts of the universe. 

Assessable learning outcomes Higher Tier only:  high demand

Explain how the Big Bang theory accounts for:
• light from galaxies is shifted to the red end of the spectrum;
• the further away galaxies are, the greater the red shift;
• the age and starting point of the Universe. 

 Unit 2: Science for the needs of society - Section 2.5 Energy Resources

2.5.4 Working waves

Foundation Tier only 
• know that electromagnetic radiation travels as waves;
• know a definition for frequency and wavelength; 
• identify the regions of the electromagnetic spectrum;

Both Tiers

• describe, in terms of wavelength and frequency the differences between the
regions of the electromagnetic spectrum; 

Higher Tier only

• recall and use the equation:
v= fλ 
where:
v is velocity
f is frequency
λ is wavelength
 

 Unit G485: Fields, particles and frontiers of Physics

Module 5 - 5.5 Modelling the Universe

Candidates should be able to:

j) select and use the equation Δλ/λ=v/c;
k) describe and interpret Hubble’s redshift observations;
l) state and interpret Hubble’s law (HSW 1 & 2);
m) convert the Hubble constant H₀ from its
conventional units (km s^-1 Mpc^-1 ) to SI (s^-1);
 

 Unit G494:Rise and Fall of the Clockwork Universe

 RF1.3 Our place in the Universe

Candidates should demonstrate evidence of:

1. knowledge and understanding of phenomena, concepts and relationships by describing:

(iv) evidence of a ‘hot big bang’ origin of the universe from:
• cosmological red-shifts (Hubble’s law);
• cosmological microwave background;
 

3. quantitative and mathematical skills, knowledge and understanding by making calculations and estimates involving:
(i) distances and ages of astronomical objects;
(ii) distances and relative velocities from radar-type measurements.