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प्रश्न
Find the odd one out and give its explanation.
विकल्प
Eye piece
Magnifier
Kaleidoscope
Telescope
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उत्तर
Kaleidoscope
Explanation-
Kaleidoscope uses mirrors while other devices make use of lenses.
APPEARS IN
संबंधित प्रश्न
(a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.
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?
An object AB is placed between O and F1 on the principal axis of a converging lens as shown in the diagram.
Copy the diagram and by using three standard rays starting from point A, obtain an image of the object AB.
Draw a labelled ray diagram to show how a ray of light passes through a parallel sided glass block:
if it hits the glass block at 90° (that is, perpendicular to the glass block)
Where should an object be placed in front of a convex lens so as to obtain its virtual, erect and magnified image?
Define the principal axis of a convex lens.
What kind of lens can form:
am erect diminished image?
Show by a diagram the refraction of two light rays incident parallel to the principal axis on a convex lens by treating it as a combination of a glass slab and two triangular glass prisms.
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
Answer the following question.
List four precautions which a student should observe while determining the focal length of a given convex lens by obtaining an image of a distant object on a screen.
State the nature and position of the object on the principal axis to obtain a real image of the same size
Write the three characteristics of the image formed by a convex lens of focal length 20 cm for the object at distance (i) 10 cm, (ii) 30 cm, (iii) 40 cm, (iv) 60 cm from the lens.
Why do we say that the ‘2F’ and ‘F’ points of a convex lens can be regarded as a sort of ‘turning points’ as far as the nature of the image formed by it is concerned?
Draw a ray diagram to illustrate the determination of the focal length of a convex lens using an auxiliary plane mirror.
_______ times larger images can be obtained by using a simple microscope.
Find the odd one out and give its explanation.
Write the name.
The lens used in simple microscope.
Write scientific reason.
Adults need bifocal lens spectacle.
Convex lens is also known as ______.
