100 Aptitude Test Problems in Physics4.2. Remote objects are viewed through a
converging lens with a focal length F =
9 cm placed at a distance a = 36 cm in
front of the eye.
Estimate the minimum size of the screen
that should be placed behind the lens so
that the entire field of view is covered.
Where should the screen be placed? Assume
that the radius r of the pupil is approxi-
mately 1.5 mm.
4.3•. A cylindrical transparent vessel of
height h (It < Ryes), where Ryes is the ra-
dius of the vessel, is filled with an ideal gas
of molar mass p. at a temperature T and a
pressure p 0. The dependence of the refrac-
tive index n of the gas on its density pobeys the law n = 1 + ctp. The vessel is
rotated at an angular velocity o about its
axis. A narrow parallel beam of light of ra-
dius Tbea m is incident along the axis of thevessel.
Determine the radius R of the spot on the
screen placed at right angles to the vessel
axis at a distance L behind the vessel, as-
suming that the change in the gas pressure
at each point of the vessel due to rotation
is small as compared with Pe. The effect of
the end faces of the vessel on the path of
the rays should be neglected.
4.4. A telescope with an angular magnifi-
cation k = 20 consists of two converging
thin lenses, viz. an objective with a focal
length F = 0.5 m and an eyepiece which
can be adjusted to the eye within the limits
between D_ = —7 D and D+ = +10 D