Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

292 Aptitude Test Problems in Physics

The distance b from the lens to point B can be

calculated by using the formula for a thin lens:

11. I^ aF
    a F =12 cm.
    = a -I- b ' u^

It is clear now that the screen must coincide with
the real image of the pupil in the plane S. Figure 226
shows that the minimum radius of the screen is

R= —

b

r 0.5 mm,

a

and the screen must be placed in the plane. S with
its centre at point B

Fig. 227

4.3*. Let us first determine the distribution of the

gas pressure near the axis of the vessel. We shall

consider the volume element Ar AS of the gas

(Fig. 227). The centripetal acceleration a = co2r