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प्रश्न
Explain with the help of a diagram, why the convex lens is also called a converging lens.
उत्तर
A convex lense is outwardly curved and causes the light to pass through it and converge or concentrate to a point. Think of a magnifying glass that is used to burn something. The light that passes through it concentrates to a point, and this convergence is used to burn things. See the diagram given below.
संबंधित प्रश्न
A student focuses the image of a well-illuminated distant object on a screen using a convex lens. After that, he gradually moves the object towards the lens and each time focuses its image on the screen by adjusting the lens.
(i) In which direction, towards the screen or away from the screen, does he move the lens?
(ii) What happens to the size of the image? Does it decrease or increase?
(iii) What happens to the image on the screen when he moves the object very close to the lens?
A student wants to project the image of a candle flame on the walls of school laboratory by using a lens:-
(a) Which type of lens should be use and why?
(b) At what distance in terms of focal length 'F' of the lens should be place the candle flame so as to get (i) a magnified, and (ii) a diminished image respectively on the wall?
(c) Draw ray diagram to show the formation of the image in each case?
A beam of light travelling in air is incident of water. Draw a ray-diagram indicating the change in its path in water.
For what position of an object a real, diminished image is formed by a convex lens?
Define principal axis, principal focus and focal length of a convex lens.
Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.
Which of the above two cases illustrates the working of a magnifying glass?
The focal lengths of four convex lenses P, Q, R and S are 20 cm, 15 cm, 5 cm and 10 cm, respectively. The lens having greatest power is :
(a) P
(b) Q
(c) R
(d) S
Define the term principal axis of a lens.
An object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find (i) the position (ii) the magnification and (iii) the nature of the image formed.
