What are paraxial rays ?

What are canot rays ? Write characteristics.

A hollow sphere of glass of R.I .n has small mark M on its interior surface which is observed by an observer O from a point outside the sphere, .C is centre of the sphere. The inner cavity (air) is concentric with the external surface and thickness of the glass is every where equal to the radius of the inner surface. Find the distance by which the mark will appear nearer than it really is in terms of n and R assuming paraxial rays.

A fly F is sitting on a glass slab A , 45 cm thick and of refractive index 3/2 . The slab covers the top of a container B containing water (Refrective index 4/3) upto a height of 20 cm . The bottom of container is closed by a concave mirror C of radius of curvature 40 cm . Locate the final image formed by all reflection assuming paraxial rays.

What are heat rays ?

A glass wedge with a small angle of refraction theta is placed at a certain distance from a converging lens with a focal length f ,one surface of the wedge being perpendicular to the optical axis of the lens. A point sources S of light is on the other side of the lens at its focus. The rays reflected from the wedge (not from base) produce, after refraction in the lens , two images of the source displaced with respect to each other by d. Find the refractive index of the wedge glass. [Consider only paraxial rays.]

Assertion:- Paraxial rays are always parallel to the principal axis. Reason:- A parallel beam parallel to principal axis converges at the focal point.

Define following for curved mirrors (1) Radius of curvature (2) Centre of curvature (3) Pole (4) Principle axis (5) Aperture (6) Principle focus (7) Focal plane (8) Focal length (9) Paraxial Rays

What is cathode rays ? Write down the characteristics .