Lens and Telescopes Flashcards
(1) The type of lens used as the objective lens is
converging
(1) The objective lens produces an image of a distant object.
The image produced by the objective lens is
upside down and smaller
(2) The objective lens produces an image of a distant object.
Describe how the position of this image can be shown
a paper / screen (between the objective and the eyepiece) (1) • move screen/lens (to and fro) (1) • to obtain an image which is in focus / clear / sharp (1)
(1) State the purpose of the eyepiece.
to magnify the image (produced
by the objective) (1)
(3) The telescope is used to look at the planet Venus.
Assume that the distance from Venus to the Earth is 39 000 000 km.
The speed of light is 300 000 000 m/s.
Calculate the time it takes for light to travel from Venus to the Earth
transposition (1)
t = x/v
substitution (1)
t = 39 000 000 000/300 000 000
evaluation (1)
130 (s)
(2) A student uses a lens to form a clear image of a house.
The image is formed on a piece of paper.
The house is a long way away.
Describe how the student should find the focal length of the lens.
measuring the {distance /
space} (1)
• between lens and {paper /
image} (1)
(3) the magnification is 40 times (40)
the focal length of the objective is 110 cm.
Calculate the focal length of the eyepiece.
rearrangement (1) ie fe = fo / M substitution (1) ie (fe =) 110 / 40 evaluation (1) ie (fe =) 2.8(cm)
(2) Describe how a reflecting telescope is different from the simple telescope
which Galileo used.
Reflecting telescope has mirror(s) (1) Galilean telescope has only lenses (1) Reflecting telescope can gather more light / can have a larger objective (1) Image viewed from the side of reflecting telescope (1) Image viewed from end of Galilean telescope. (1)
(1) The type of lens used as the objective lens is
converging
(1) The ray of light changes direction when it enters the glass block because there
is a change of
speed
(2) Modern telescopes can provide us with more data than the telescopes used
100 years ago.
Explain what additional data can be collected and processed using modern
telescopes.
Different/more wave(length)s/frequencies (now) detected/collected (1) • because telescopes positioned above Earth’s atmosphere or by radio telescopes (1) OR • weaker signal(s) (now) detected/collected (1) • because modern telescopes are more powerful/have greater magnification or positioned above Earth’s atmosphere/ on top of mountains (1)
(1) Which of the lines show the possible path of a ray of light passing from air
into glass?
air: ray angled towards the normal on boundary
Glass: ray angled away from normal
(1) The wave is refracted at the boundary between deep water
and shallow water.
What happens when the wave is
refracted?
Changes speed
Changes direction
(3) Explain how a refracting telescope produces a magnified image of Jupiter.
the (objective) lens (1) • collects light (from Jupiter) (1) • focuses/converges/refracts the light (1) • (objective) produces a real image (1) • (at the) focal point (1) • (Image is viewed by the) eyepiece lens (1) • (Eyepiece) produces a virtual image (1)
