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Name the type of lens whose power is positive.
The image of an object formed by a lens is real, inverted and of the same size as the object. If the image is at a distance of 40 cm from the lens, what is the nature and power of the lens ? Draw ray diagram to justify your answer.
Concept: Power of a Lens
A student obtained on a screen the sharp image of a candle flame placed at the farther end of laboratory table using a concave mirror. For getting better value of focal length of the mirror, the teacher suggested to him to focus the sun. What should the student do?
(A) Should move the mirror away from the screen.
(B) Should move the mirror towards the screen.
(C) Should move the mirror and screen both towards the sun.
(D) Should move only the screen towards the sun.
Concept: Spherical Mirrors
State the types of mirrors used for (i) headlights and (ii) rear view mirror, in cars and motorcycles. Give to justify your answer in each case.
Concept: Spherical Mirrors
Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see:
(1) a blurred image on the wall of the laboratory.
(2) an erect image of the tree on the lens.
(3) no image as the screen has been removed
(4) an inverted image of the tree at the focus of the lens.
Concept: Power of a Lens
What is atmospheric reflection? Explain with the help of a labelled diagram that the position of a star as seen by us is not its true position.
Concept: Refraction of Light
List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
Concept: Refraction of Light
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to `1/3` rd of its size . Find the distance of the object from the optical centre of the lens .
Concept: Refraction of Light
List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.
Concept: Refraction of Light
A real image is formed by the light rays after reflection or refraction when they:
- actually meet or intersect with each other.
- actually converge at a point.
- appear to meet when they are produced in the backward direction.
- appear to diverge from a point.
Which of the above statements are correct?
Concept: Refraction of Light
Answer the following question.
Write the modification in the curvature of the eye lens which enables us to see the nearby objects clearly?
Concept: Spherical Mirrors
In torches, search lights and headlights of vehicles the bulb is placed ______.
Concept: Spherical Mirrors
Rohit wants to have an erect image of an object using a converging mirror of focal length 40 cm.
- Specify the range of distance where the object can be placed in front of the mirror. Justify.
- Draw a ray diagram to show image formation in this case.
- State one use of the mirror based on the above kind of image formation.
Concept: Spherical Mirrors >> Image Formation by Concave Mirror
An object is kept at a distance of 1m from a lens of power +2D:
- Identify the type of lens.
- Calculate its focal length and distance of the image formed.
Concept: Power of a Lens
A 10 cm long pencil is placed 5 cm in front of a concave mirror having a radius of curvature of 40 cm.
- Determine the position of the image formed by this mirror.
- What is the size of the image?
- Draw a ray diagram to show the formation of the image as mentioned in part (i).
Concept: Spherical Mirrors >> Image Formation by Concave Mirror
In the following ray diagram the correctly marked angle are:
(a) ∠i and ∠e
(b) ∠A and ∠D
(c) ∠i, ∠e and ∠D
(d) ∠r, ∠A and ∠D
Concept: Dispersion of Light
A person needs a lens of power -5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision and (ii) near vision?
Concept: Defects of Vision and Their Corrections > Presbyopia
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
Concept: Defects of Vision and Their Corrections > Myopia
What happens to the image distance in the eye when we increase the distance of an object from the eye?
Concept: Human Eye
In the following diagram, the correctly marked angles are
(A) All
(B) Only ∠i and ∠A
(C) ∠i, ∠r and ∠A
(D) ∠i, ∠A and ∠D
Concept: Dispersion of Light
In an experiment to trace the path of a ray of light through a triangular glass prism, a student would observe that the emergent ray
(a) is parallel to the incident ray.
(b) is along the same direction of incident ray.
(c) gets deviated and bends towards the thinner part of the prism.
(d) gets deviated and bends towards the thicker part (base) of the prism.
Concept: Dispersion of Light
