11B.4 The Age Of The Universe

Question 1

what is red shift

Answer 1

the apparent change in wavelength of a star’s spectrum, caused by the increasing separation between the star and earth

Question 2

what is Doppler’s effect

Answer 2

the effect that an observer who is receiving waves emitted from a moving body observes that the wavelength of the waves has been altered, to a new wavelength, as a consequence of the relative motion

Question 3

if a galaxy or a star has red shift it shows that

Answer 3

it is travelling away from us because its wavelength has been stretched

Question 4

if a galaxy or a star has a blue shift it shows that

Answer 4

it is travelling towards us as the wavelengths are compressed

Question 5

what is the formula to calculate the amount of red shift a galaxy exhibits, z,

Answer 5

z = dΛ/Λ = df/f = v/c

Question 6

what is Hubble’s law

Answer 6

the recession velocity of a galaxy is directly proportional to the distance to it

Question 7

according to Hubble’s law recession velocity is equal to

Answer 7

v = Ho d

Question 8

what is Hubble’s constant

Answer 8

the constant of proportionality in Hubble’s law Ho = 70.9 km/s Mpc

Question 9

how can we determine Ho

Answer 9

plotting a stars recession velocity against the distance to it, and the gradient is equal to Ho

Question 10

what is the expression for the To (age of the universe)

Answer 10

To =1/Ho (how to get their is page 195)

Question 11

what is big bang theory

Answer 11

the theory that the universe expanded outwards. from the single point to the currently observed situation

Question 12

what is rescission velocity

Answer 12

the speed at which one object is moving away from another object