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Question
Find the odd one out and give its explanation.
Options
Eye piece
Magnifier
Kaleidoscope
Telescope
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Solution
Kaleidoscope
Explanation-
Kaleidoscope uses mirrors while other devices make use of lenses.
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RELATED QUESTIONS
A student is using a convex lens of focal length 18 cm to study the image formation by it for the various positions of the object. He observes that when he places the object at 27 cm, the location of the image is at 54 cm on the other side of the lens. Identify from the following diagram the three rays that are obeying the laws of refraction and may be used to draw the corresponding ray diagram.
(A) 1, 2 and 4
(B) 1, 3 and 5
(C) 2, 4 and 5
(D) 2, 3 and 4
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?
An object 5 cm is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position, nature and size of the image.
A 1 cm high object is placed at a distance of 2f from a convex lens. What is the height of the image formed?
Where should an object be placed in front of a convex lens so as to obtain its virtual, erect and magnified image?
For what position of an object a real, diminished image is formed by a convex lens?
Distinguish between a convex lens and concave lens. Which of the two is a converging lens : convex lens of concave lens?
Explain with the help of a diagram, why the convex lens is also called a converging 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.
List some things that convex lens and concave mirror have in common.
A convex lens produces an inverted image magnified three times of an object placed at a distance of 15 cm from it. Calculate the focal length of the lens.
A beam of parallel light rays is incident through the holes on one side of a box and emerges out through the holes on its opposite side as shown in the diagram below:
Which of the following could be inside the box?
A convex lens of focal length 10 cm is placed in contact with a concave lens of focal length 20 cm. The focal length of this combination of lenses will be:
(a) +10 cm
(b) +20 cm
(c) −10 cm
(d) −20 cm
A lens forms an inverted image of an object. Name the kind of lens.
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.
Out of the two lenses one concave and the other convex state which is a convergent or a divergent type of a lens. Give a reason for your answer.
State the nature and position of the object on the principal axis to obtain a real image of the same size
Where should an object be placed in front of a convex lens so as to form an inverted and enlarged image? Will the image be real or virtual? Draw a ray diagram to illustrate your answer.
Draw a ray diagram to illustrate the determination of the focal length of a convex lens using an auxiliary plane mirror.
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The above images are that of a specialized slide projector. Slides are small transparencies mounted in sturdy frames ideally suited to magnification and projection since they have a very high resolution and a high image quality. There is a tray where the slides are to be put into a particular orientation so that the viewers can see the enlarged erect images of the transparent slides. This means that the slides will have to be inserted upside down in the projector tray.
To show her students the images of insects that she investigated in the lab, Mrs. Iyer brought a slide projector. Her slide projector produced 500 times enlarged and inverted image of a slide on a screen 10 m away.
a. Based on the text and data given in the above paragraph, what kind of lens must the slide projector have?
b. If v is the symbol used for image distance and u for object distance then with one reason state what will be the sign for `"ЁЭСг"/"ЁЭСв"` in the given case?
c. A slide projector has a convex lens with a focal length of 20 cm. The slide is placed upside down 21 cm from the lens. How far away should the screen be placed from the slide projector’s lens so that the slide is in focus?
OR
c. When a slide is placed 15 cm behind the lens in the projector, an image is formed 3 m in front of the lens. If the focal length of the lens is 14 cm, draw a ray diagram to show image formation. (not to scale)
