image formation in lenses using ray diagram and its laws
Answers
Explanation:
hope this answer helps you
Answer:
Rules for obtaining images formed by convex lens
In convex lens, the image is always formed at a point where at least two refracted light rays meet.
Rule 1: A ray of light which is originally parallel to the principal axis passes through the focus after refraction through the lens.
Rule 2: A ray of light passing through the optical centre of the convex lens does not bent after refraction but goes straight. Also, a ray of light going along the path of principal axis of a convex lens also goes straight and does not deviate.
Rule 3: When a ray of light passes through the focus of the convex lens then it becomes parallel to the principal axis after refraction through the lens.
Types of images formed by a convex lens
The type of image formed by a convex lens depends on the position of the image.
Case 1: If the object is placed between optical centre and focus (between C and F’) then the first ray of light starting from the top of the object is parallel to the principal axis. Therefore, as per the rule, it passes through another focus after refraction through the lens. Another ray of light from the object passes through the optical centre of the lens and thus as per the rule goes straight after refraction through the lens. Thus, both the light rays diverge after refraction through the lens and does not meet. Therefore, both the refracted rays are produced backwards so that they meet at a point to form an image.
The image formed will be: Behind the object, virtual and erect and larger than the object.
Case 2: When the object is placed at the focus of the convex lens (at F’) then it means that the object is placed at the distance equal to the focal length of the lens.
One ray of light becomes parallel to the principal axis of the lens and thus, passes through another focus after refraction through the lens. Another ray of light passes through the optical centre of the lens and goes straight.
Therefore, the image formed is: At infinity, Real and inverted, highly enlarged.
Case 3: When the image is placed between focus and distance less than twice the focal length (F’ and 2F’) then a ray of light parallel to the principal axis of the lens passes through another focus (F) after refraction through the lens. Another ray of light passes through optical centre of the lens and goes straight.
Therefore, the image formed is: Real and inverted, Larger than object and beyond 2F.
Case 4: When the object is paced at the distance equal to twice the focal length ( at 2F’) of the convex lens then one ray of light becomes parallel to the principal axis and passes through another focus of the lens after refraction. Another ray of light passes though optical centre and goes straight after refraction. Both the refracted light rays meet at 2F` on another side.
The image formed is: Real and inverted, same size as that of an object.
Case 5: When the object is placed at the distance greater than twice the focus (beyond 2F’) one ray of light becomes parallel to principal axis and passes through focus after refraction through the lens and another light ray passes through optical centre and goes straight after refraction.
The image formed is: Between F and 2F, Real and inverted, Smaller than object.
Case 6: When the object is placed at infinity, the light rays become parallel after reaching the lens.
The image formed is: At the focus on another side, Real and inverted, highly diminished.