Page 51 - Physics 10_Float

GEOMETRICAL OPTICS

(c) Object between F and 2F

Object F 2F
2F F
Image

The image is beyond 2F, real, inverted, larger than the object. Approximations
The thin lens formula assumes
(d) Object at F
the lenses have no thickness.
This is a good assumption
Object F when objects and images are
F far away compared with the
thickness of a lens.

No image is formed because the refracted rays are
parallel and never meet.
(e) Object between lens and F

Image
For your information
Object F The study of light behaviour is
called optics. The branch of
F
optics that focuses on the
creation of images is called
geometrical optics, because it is
The image is behind the object, virtual, erect, larger than the object. based on relationships
Fig. 12.25
between angles and lines that
12.10 IMAGE LOCATION BY LENS EQUATION describe light rays. With a few

rules from geometry, we can
In Fig.12.26, let an object OP is placed in front of a convex lens explain how images are formed
at a distance p. A ray PR parallel to the principal axis after by devices like lenses, mirrors,
refraction passes through focus F. Another ray PC meets the cameras, telescopes, and
first ray at point P after passing through the optical centre C. ’ microscopes. Optics also
includes the study of the eye
If this process is repeated for the other points of the object, a
itself because the human eye
real and inverted image O’P’ is formed at a distance q from forms an image with a lens.
the lens. p Thin lens
R
P
Image
F O’
O
Object F’ C
f
P’
Fig.12.26
q
Not For Sale – PESRP 51