Physics
OPTICS
Lens
A lens is a transmissive optical device that focuses or disperses a light beam by
means of refraction.
Converging lens
Diverging lens
03/17
Convex Lenses
Thicker in the centre than at the edges
• Lens that converges (brings
together) light rays.
• Forms real images or virtual
images depending on the position
of the object.
04/17
Concave Lenses
Lenses that are thicker at the edges
and thinner in the centre.
• Diverges light rays
• All images are erect and
reduced.
05/17
Components of Lens
06/17
Image Formation in Convex Lens
08/17
Image Formation in Convex Lens
Image Formation in Concave Lens
09/17
DEFECTS IN EYE
MYOPIA HYPERMETROPIA
• Short sightedness, • Long sightedness,
lengthening of eye shortening of eye
ball. ball.
• Defect corrected by • Image of nearby
concave lens objects forms behind
• Image of distant retina
objects formed • Correction – convex
before retina lens
QUESTIONS
1.The lens-type commonly used for correcting presbyopia is .
(a) bifocal lens
(b) cylindrical lens
(c) convex lens
(d) concave lens
QUESTIONS
2. Mirror used to see large images of teeth of patients is .
(a) ZigZag Mirror
(b) Plane Mirror
(c) Convex Mirror
(d) Concave Mirror
QUESTIONS
3. What lens will the ophthalmologist recommend to correct
hypermetropia?
(a) Bifocal
(b) Concave
(c) Progressive
(d) Convex
4. Image formed by a Plane Mirror is always .
a) Virtual and Erect
b) Real and Erect
c) Real and Inverted
d) Virtual and Inverted
5. Myopia’ is also known as:
(a) near-sightedness
(b) Astigmatism
(c) presbyopia
(d) far-sightedness
6. Which of the following mirror is used in vehicles as a headlight?
a) Double Convex mirror
b) Plane mirror
c) Concave mirror
d) Convex mirror
7. An image formed on a screen is called a image, whereas the
image formed by a plane mirror is called a image.
(a) real; virtual
(b) parabolic; perpetual
(c) virtual; real
(d) vector; layered
8. Which of the following types of mirrors show a lateral inversion of light?
(a) Convex mirror
(b) Concave mirror
(c) Rectangle mirror
(d) Plane mirror
9. Which type of lens is used in microscope?
(a) Bifocal
(b) Concave
(c) Progressive
(d) Convex
10. What will be the size of the image formed by a concave mirror when an object
placed between Pole and Focus? SSC MTS 07/08/2019(Morning)
(a) Same Size
(b) Enlarged
(c) Point Size
(d) Diminished
