# Scientists have observed that the wavelengths of the light from galaxies moving away from the Earth are longer than expected.

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Red-Shift and Big Bang Qs

Q1.(a)    Scientists have observed that the wavelengths of the light from galaxies moving away from the Earth are longer than expected.

(i)      What name is given to this observation?

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(1)

(ii)     Draw a ring around the correct answer to complete each sentence.

 light can be stretched. This observation gives scientists evidence that galaxies are changing colour. the Universe is expanding.

(1)

(iii)    There is a pattern linking the size of the observed increase in the wavelengths of light from a galaxy and the distance the galaxy is from the Earth.

Which one of the graphs, L, M or N, shows the correct pattern?

Write the correct answer in the box.

(1)

Which one of the following questions cannot be answered by scientists?

Tick () one box.

 How old is the Universe? Why was the Universe created? How fast does light travel through the Universe?

(1)

(Total 4 marks)

Q2.The diagram shows a teacher using a loudspeaker to demonstrate an important effect.
The loudspeaker, which produces a note of constant frequency, is swung around in a circle.

(a)     As the loudspeaker moves towards the students, the frequency of the note heard by the students increases.

What happens to the note heard by the students as the loudspeaker moves away from them?

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(1)

(b)     The teacher is using the demonstration to model the red-shift in light that is observed from most distant galaxies.

(i)      Which one of the following statements gives the main reason why models are used in science?

 Models can help to explain an effect or theory.

 Models can prove that a theory is correct.

 Models can help to generate new ideas.

(1)

(ii)     Explain how this demonstration can be used as a model for red-shift.

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(2)

(c)     Red-shift provides evidence to support the theory that the Universe began from a very small initial point.

What name is given to this theory?

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(1)

(Total 5 marks)

Q3.(a)     A lorry has an air horn. The air horn produces sound waves in the air.

(i)      Use one word to complete the following sentence.

Sound waves cause air particles to ................................................................. .

(1)

(ii)     The air horn produces sound waves at a constant frequency of 420 Hz.

The wavelength of the sound waves is 0.80 m.

Calculate the speed of the sound waves.

Use the correct equation from the Physics Equations Sheet.

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Speed = .......................................................... m/s

(2)

(b)     A person standing at the side of the road, as the lorry goes past, hears the sound from the air horn change pitch.

(i)      What determines the pitch of a sound?

Draw a ring around the correct answer.

 amplitude frequency loudness

(1)

(ii)     As the lorry moves away from the person, the air horn continues to produce sound waves with a wavelength of 0.80 m.

What is the wavelength of the sound waves the person heard?

Draw a ring around the correct answer.

 shorter than 0.8 m equal to 0.8 m longer than 0.8 m

(1)

(iii)    The sound waves the person heard from the moving air horn are different to the sound waves the air horn produced.

What name is given to this effect?

Draw a ring around the correct answer.

 diffraction Doppler refraction

(1)

(Total 6 marks)

Q4.          (a)     A student listens to the sound waves produced by a car siren. When the car is stationary, the student hears a constant frequency sound.

Describe how the wavelength and frequency of the sound waves heard by the student change when the car is driven away from the student.

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(2)

(b)     Satellites fitted with various telescopes orbit the Earth. These telescopes detect different types of electromagnetic radiation.

Why are telescopes that detect different types of electromagnetic waves used to observe the Universe?

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(1)

(c)     In 2005 a space telescope detected a star that exploded 13 billion years ago. The light from the star shows the biggest red-shift ever measured.

(i)      What is red-shift?

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(1)

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(1)

(d)     Red-shift provides evidence for the ‘big bang’ theory.

(i)      Describe the ‘big bang’ theory.

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(2)

(ii)     Suggest what scientists should do if new evidence were found that did not support the ‘big bang’ theory.

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(1)

(Total 8 marks)

Q5.Galaxies emit all types of electromagnetic wave.

(a)    (i)      Which type of electromagnetic wave has the shortest wavelength?

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(1)

(ii)     State one difference between an ultraviolet wave and a visible light wave.

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(1)

(b)     Electromagnetic waves travel through space at a speed of 3.0 x 108 m/s.

The radio waves emitted from a distant galaxy have a wavelength of 25 metres.

Calculate the frequency of the radio waves emitted from the galaxy and give the unit.

Use the correct equation from the Physics Equations Sheet.

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Frequency = ......................................................................

(3)

(c)     Scientists use a radio telescope to measure the wavelength of the radio waves emitted from the galaxy in part (b) as the waves reach the Earth. The scientists measure the wavelength as 25.2 metres. The effect causing this observed increase in wavelength is called red-shift.

(i)      The waves emitted from most galaxies show red-shift.

What does red-shift tell scientists about the direction most galaxies are moving?

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(1)

(ii)     The size of the red-shift is not the same for all galaxies.

What information can scientists find out about a galaxy when they measure the size of the red-shift the galaxy produces?

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(2)

(iii)    What does the observation of red-shift suggest is happening to the Universe?

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(1)

(Total 9 marks)

Q6.(a)     Observation of the spectra from distant galaxies provides evidence to support the ‘Big Bang’ theory.

(i)      Complete the following sentence.

Many scientists think that the ‘Big Bang’ theory describes the ............

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(1)

(ii)     Tick () one box to complete the sentence.

The discovery of cosmic microwave background radiation was important

because it ...

 proved the ‘Big Bang’ theory to be correct. provided more evidence to support the ‘Big Bang’ theory. proved the Universe will continue to expand forever.

(1)

(b)     Many stars are part of a binary star system. Binary star systems have two stars.

The visible spectrum from stars includes dark lines. These lines are at specific wavelengths.

The diagram shows the position of two dark lines in the spectrum from the Sun. It also shows the same lines in the spectra from two stars A and B in a binary star system at the same point in time.

(i)      What name is given to the effect shown in the spectrum from star A?

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(1)

(ii)     Scientists have concluded that the two stars in a binary star system orbit around a fixed point between the two stars.

A comparison of the spectra from the two stars in a binary star system provides evidence to support this conclusion.

Explain how.

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(3)

(Total 6 marks)

M1.(a)     (i)      red-shift

accept Doppler (effect)

1

(ii)     the Universe is expanding

1

(iii)    N

1

(b)     Why was the Universe created?

1

[4]

M2.          (a)     frequency / pitch decreases

accept wavelength increases

accept it / the note becomes deeper / lower

it / the note decreases is insufficient

quieter is neutral

1

(b)     (i)      Models can help to explain an effect or theory.

1

(ii)     (moving) loudspeaker represents the (moving) galaxy

accept sound waves represent light waves

1

the decrease in frequency of the sound is like red-shift

accept increase in frequency is like blue-shift

accept answers in terms of wavelength change

accept sound going away from you is like red-shift

accept red-shift happens when galaxies / stars move away (from Earth)

this accept only scores if first marking point scores

1

(c)     big bang

1

[5]

M3.(a)     (i)      vibrate / oscillate

accept a correct description

move is insufficient

1

(ii)     336

allow 1 mark for correct substitution, ie 420 × 0.8(0) provided no subsequent step shown

2

(b)     (i)      frequency

1

(ii)     longer than 0.8m

1

(iii)    Doppler

1

[6]

M4.          (a)     wavelength increases

accept the crests are further apart

ignore waves are further apart

1

frequency decreases

accept pitch decreases

ignore references to amplitude

1

(b)     stars / galaxies / sources emit all / different types of electromagnetic waves /

accept two or more named electromagnetic waves

accept answers in terms of frequencies / wavelengths

1

(c)     (i)      wavelength (of light) increases

accept frequency decreases

or

light moves to red end of spectrum

accept redder but do not accept red alone

1

(ii)     it is the star (detected) furthest from the

Earth

accept galaxy for stars

or

it is moving away the fastest

ignore reference to universe expanding

1

(d)     (i)      all matter compressed to / starts at / comes from a single point

do not accept increasing gravitational pull

accept everything / the universe for all matter

1

(massive) explosion sends matter outwards

accept explosion causes universe to expand

ignore explosion creates the universe or further reference to star / Earth formation

1

(ii)     check validity / reliability of the evidence

or

change the theory to match the new evidence

accept comparison of new and old evidence

1

[8]

M5.(a)     (i)      gamma

accept correct symbol

1

(ii)     any one from:

•         (ultraviolet has a) higher frequency

ultraviolet cannot be seen is insufficient

•         (ultraviolet has a) greater energy

•         (ultraviolet has a) shorter wavelength

ignore ultraviolet causes cancer etc

1

(b)      1.2 × 107 / 12 000 000

allow 1 mark for correct substitution, ie 3 × 108 = f × 25

2

hertz / Hz / kHz / MHz

do not accept hz or HZ

answers 12 000 kHz or 12 MHz gain 3 marks

for full credit the numerical answer and unit must be consistent

1

(c)     (i)       away (from each other)

accept away (from the Earth)
accept receding

1

(ii)     distance (from the Earth)

accept how far away (it is)

1

speed galaxy is moving

1

(iii)    (Universe is) expanding

1

[9]

M6.(a)     (i)       origin of the Universe

accept (why) the Universe is expanding

do not accept origin of the Earth

1

(ii)      provided more evidence to support the ‘Big Bang’ theory

1

(b)     (i)       red-shift

accept Doppler (shift)

1

(ii)      (at the point in time shown the observed spectrum from) star A (shows it) is moving away from the Earth

accept star A is moving away

star A shows red-shift is insufficient

1

light from star B shows a decrease in wavelength

accept light from star B shows blue-shift

accept light from star B shows an increase in frequency

1

1

[6]

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