When a wave undergoes reflection at an interface from rarer to denser medium, change in its phase is:
Draw a ray diagram to show the formation of an image at the least distance of distinct vision, by a compound microscope.
Obtain an expression for its angular magnification.
A lens is a portion of a transparent medium bounded by two surfaces and one of these surfaces is essentially spherical. It is used to converge or diverge the light incident on it. Power of a lens is the measure of its ability to converge or diverge the light incident on it. Power of a lens depends on the refractive index of the material of lens with respect to the surrounding medium and the radii of curvature of its two surfaces.
A beam of light coming parallel to the principal axis of a convex lens L1 of focal length 15 cm is incident on it. Another convex lens L2 of focal length 25 cm is placed coaxially at a distance d from L1. For the final image to be formed at infinity, the value of d should be:
a. Define the term resolving power of a telescople. How will the resolving power be effected with the increase in i. Wavelength of light used. ii. Diameter of the objective lens. Justify your answers. b. A screen is placed 80 cm from an object. The image of the object on the screen is formed by a convex lens placed between them at two different locations separated by a distance 20 cm. Determine the focal length of the lens.
A converging lens is kept in contact with a diverging lens; both the lenses being of equal focal lengths.
What is the focal length of the combination?
A lens is a transparent optical medium bounded by two surfaces; at least one of which should be spherical. Considering image formation by a single spherical surface successively at the two surfaces of a lens, lens maker's formula is obtained. It is useful to design lenses of desired focal length using surfaces of suitable radii of curvature. This formula helps us obtain a relation between u, v and f for a lens. Lenses form images of objects and they are used in a number of optical devices, for example microscopes and telescopes.
Two convex lenses A and B of focal lengths 15 cm and 10 cm respectively are placed coaxially d distance apart. A point object is kept at a distance of 30 cm in front of lens A. Find the value of d so that the rays emerging from lens B are parallel to its principal axis.
A ray of light passes through a prism of refractive index √2 as shown in the figure.
Find the angle of incidence (∠r2) at face AC.
Find the angle of minimum deviation for this prism.
The human eye has an approximate angular resolution of = 5.8 10-4 rad and a typical photoprinter prints a minimum of 300 dpi (dots per inch, 1 inch = 2.54cm).
At what minimal distance z should a printed page be held so that one does not see the individual dots?
The following table gives the values of the angle of deviation for different values of the angle of incidence for a triangular prism.
Angle of incidence | 33o | 38o | 42o | 52o | 60o | 71o |
Angle of deviation | 60o | 50o | 46o | 40o | 43o | 50o |
For what value of the angle of incidence, is the angle of emergence likely to be equal to the angle of incidence itself?
Draw a ray diagram showing the passage of a ray of light through this prism when the angle of incidence has the above value.