Principal Focus

Draw the course of a rays for tracing image of an object held between pole and principal focus of a concave mirror. State the position and nature of image formed. or Draw the course of rays for tracing image of an object held between optical centre and principal focus of a convex lens. State the nature of image formed.

With a concave mirror, an object is placed at a distance x_(1) from the princiipal focus, on the principal axis. The image is formed at a distance x_(2) from the principal focus. The focal length of the mirror is

The rays of light falling on a convex lens in a direction parallel to principal axis of the lens, get refracted through the lens and meet actually at a single point F on the principal axis of the lens. This point is called principal focus of the lens. Read the above passage and answer the following questions : (i) Is principal focus of a convex lens, a real point ? Is the same true for a concave lens ? (ii) A distinct image of a distant tree os obtained on a screen held at 40 cm from a convex lens. What is its focal length ? (iii) Our teachers and parants advise us to stay focussed. What does it imply ?

With reference to spherical lenses, state the meaning of the following terms or define the following terms and draw the diagrams to illustrate the same : (1) centre of curvature (C) (2) radii of curvature (R_(1),R_(2)) (3) principal axis (4) optical centre (O) (5) principal focus (F) (6) focal length (f)

Figure shows an object located at point P, 0.25 meter from concave spherical mirror with principal focus F. The focal length of the mirror is 0.10m How does the image change if the object is moved from point P toward point F?