A cylindrical vessel, whose diameter and height both are equal to 30 cm, is placed on a horizontal surface and a small particle P is placed in it at a distance of 5.0 cm from the center. An eye is placed at a position such that the edge of the bottom is just visible (see figure 18-E8). The particle P is in the plane of drawing. Up to what minimum height should water be poured in the vessel to make the particle P visible?

For the given cylindrical vessel;

Diameter (d) = 30cm

Radius () = 15 cm

Height (h) = 30 cm

d = height of water

The refractive index of water is 1.33 =

By applying Snell’s law:

Angle of refraction = r =

(Point P will be visible when the angle of refraction becomes)

Let, the distance from P to X be x cm.

----- (i)

Now,

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