The origin of the Universe

This question is about cosmic microwave background radiation (CMBR) and the Big Bang.

CMBR has a mean frequency of 1.6 × 10¹¹Hz.

State the formula linking wave speed, frequency and wavelength.

Show that the mean wavelength of CMBR is about 2 mm.

[speed of light = 3.0 × 10⁸m/s]

CMBR was first released after the Big Bang.

When CMBR was first released it had a wavelength of about 9 × 10^–5mm, but now it has a wavelength of about 2 mm.

Using this information, explain how CMBR supports the Big Bang theory.

Explain how the cosmological red‑shift of galaxies also supports the Big Bang theory.

This question is about cosmology.

Give two pieces of evidence that support the Big Bang theory.

The galaxy NGC 300 is moving away from the Earth at a speed of 1.44 × 10⁵m/s.

Hydrogen atoms in NGC 300 emit light with a reference wavelength of 4.3405 × 10⁻⁷m.

Calculate the wavelength of this light when it is detected at Earth.

Give your answer to five significant figures.

[speed of light in a vacuum, c = 3.00 × 10⁸m/s]

Another galaxy, Centaurus A, is much further away from the Earth than NGC 300.

Explain how the wavelength of light detected from hydrogen atoms in Centaurus A is different from the wavelength of light detected from hydrogen atoms in NGC 300.

A glass prism can be used to refract light.

State the name of the piece of equipment used to measure angles.

Measure the angle of incidence and the angle of refraction for the light entering the prism.

angle of incidence =_........ degrees

angle of refraction =_........ degrees

State the formula linking refractive index, angle of incidence and angle of refraction.

Calculate the refractive index of the glass.

Two galaxies, A and B, emit red light with a reference wavelength of 630 nm.

An astronomer measures the wavelength of red light from galaxy A when the light arrives at the Earth.

The astronomer’s value for the wavelength is 645 nm.

Calculate the difference between the astronomer’s value for the wavelength and the reference wavelength of red light.

The change in wavelength happens because galaxy A is moving away from the Earth.

Calculate the speed of galaxy A.

[speed of light = 3.0 × 10⁸m / s]

Light from galaxy B has twice the redshift as light from galaxy A.

Galaxy B is twice as far away from Earth as galaxy A.

Explain how these observations support the Big Bang theory of the origin of the Universe.

This question is about stars.

The table gives some information about four stars.

Star C is much more powerful than star A.

Stars A and C appear to have the same brightness when viewed from Earth.

Suggest how this is possible.

Using information from the table, explain which star is in the supernova stage of its evolution.

Explain how a main sequence star evolves into a supernova.

Astronomers have used supernovas in distant galaxies to investigate the expansion of the universe.

Light emitted from a supernova at a wavelength of 7.77410^–7m was detected at Earth with a wavelength of 7.78010^–7m.

Calculate the speed at which the galaxy containing this supernova was moving away from the Earth.

[speed of light = 3.010⁸m / s]

The astronomers investigated supernovas that showed a red-shift in the wavelengths detected in different galaxies.

The astronomers discovered that the red-shifted light detected from supernovas in nearby galaxies had shorter wavelengths than the red-shifted light detected from supernovas in galaxies further away.

Explain how this discovery supports the Big Bang theory.

A binary star system has two nearby stars, which orbit each other in a circular path around a common centre of gravity.

In an eclipsing binary system, one star passes behind the other star in its orbit. This causes a decrease in the light intensity of the binary star system when viewed from Earth.

The graph shows how the light intensity of the binary star system changes with time.

Suggest why the decreases in light intensity are not all the same.

Use the graph to determine the time period of the binary star system.

One of the stars in this binary system has an orbital speed of 19 km/s.

Calculate the orbital radius of this star.

A different binary star system is in a distant galaxy.

When observed from the Earth, light from this galaxy has a longer wavelength than the wavelength of the light when it is emitted from the galaxy.

Explain why this gives evidence for the Big Bang theory.

This question is about astrophysics.

The table lists some statements about the universe.

Place ticks (✓) in the table to show which statements support the Big Bang theory.

The Sun will become a red giant star when it leaves the main sequence.

Which row correctly describes how the surface temperature and brightness of the Sun will change when it becomes a red giant?

Astronomical objects can be classified by their absolute magnitude.

State what is meant by the term absolute magnitude.

The Big Bang theory describes the evolution of the universe.

Explain how cosmic microwave background radiation (CMBR) supports the Big Bang theory.

Hydrogen gas in a laboratory on Earth emits light with a wavelength of 605 nm.

A distant galaxy contains hydrogen which emits light of the same wavelength.

The wavelength of the light from the distant galaxy is measured as 683 nm on Earth.

Calculate the speed of the distant galaxy.

[speed of light = 3.010⁸m/s]

The Big Bang theory suggests that the Universe is approximately 14 billion years old.

Describe the evolution of the Universe from the Big Bang until the present day.

Describe the evidence that supports the Big Bang theory.

Diagram 1 shows two identical buzzers connected with springs.

Spring A is connected to a post.

A force acts on the apparatus for a short period of time, pulling both buzzers to the right.

During this time, buzzer A moves 2 cm and buzzer B moves 4 cm.

Explain why buzzer B travels with twice the average speed of buzzer A.

A student connects the microphone to an oscilloscope to measure the frequency of sound from the two buzzers while the force acts on the arrangement.

Explain the difference in the measured frequencies of sound from buzzer A compared to buzzer B.

Diagram 2 shows an oscilloscope trace.

The trace represents the sound wave received by the microphone from buzzer A.

Measure the period of the sound waves from buzzer A.

Give your answer in standard form.

Diagram 3 shows two distant galaxies and the Earth.

Light emitted from a nearby star has a wavelength of 590 nm.

The light from an identical star in galaxy P arrives at the Earth.

The wavelength of the light from the star in galaxy P is 600 nm.

Calculate the change in wavelength for light from the star in galaxy P.

Galaxy Q is twice as far away from the Earth as galaxy P.

Suggest how the speed of galaxy Q relates to the speed of galaxy P.

Suggest a value for the change in wavelength of light from an identical star in galaxy Q when the light arrives at the Earth.

Explain how comparing the speeds of the two galaxies provides evidence for the Big Bang theory.

Give two pieces of evidence for the Big Bang theory.

Explain how this evidence supports the Big Bang theory.