Astronomy
> Planetary Astronomy |
DCS#
8B10.02 |
PARALLAX
-
APPARATUS
tall
ringstand
|
201A |
grid
|
|
document
camera or laptop
|
|
DESCRIPTION
Use the
document camera
or laptop to project a grid onto the projection screen. Place the
tall
ringstand about 3 m in front of the screen. Students are asked to
note the change in position of the ringstand against the background
grid with first one eye closed and then the other.
They can estimate
their distance d from
the ringstand by measuring its angular shift. They are given the
distance between the gridlines so they can express the shift x in meters. Then, if h is the distance from the tall
object to the screen and x is
the distance that the object
appears to shift against the background grid, their
distance
from the object is:
d =
baseline/p where baseline (distance between eyes) ~ 6
cm
and p
= x/h