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प्रश्न
Distinguish between:
Concave lens and Convex lens
State the differences between images formed by a convex and a concave lens.
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उत्तर
| Concave lens | Convex lens | |
| 1. | It is a diverging lens because it diverges the rays falling on it. | It is a converging lens because it converges the rays falling on it. |
| 2. | It is thin at the center and bulged at the edge. | It is thin at the edge and bulged at the centre. |
| 3. | The image formed by concave lens is always diminished and virtual. | The image formed by convex lens can be real as well as virtual. Also, the image formed can be diminished as well as magnified. |
| 4. | It has a virtual focus. | It has a real focus. |
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संबंधित प्रश्न
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.
Where should an object be placed so that a real and inverted image of the same size as the object is obtained using a convex lens?
A ray of light travelling in water emerges into air. Draw a ray-diagram indicating the change in its path.
A ray of light travelling in air is incident on a parallel-sided glass slab (or rectangular glass slab). Draw a ray-diagram indicating the change in its path in glass.
Draw a labelled ray diagram to show the angle of incidence and the angle of refraction for a refracted ray of light.
For what position of an object a real, diminished image is formed by a convex lens?
If an object is at a considerable distance (or infinity) in front of a convex lens, where is the image formed?
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.
Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:
0.50 m
Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:
0.15 m
Which causes more bending (or more refraction) of light rays passing through it : a convex lens of long focal length or a convex lens of short focal length?
Define the term principal axis of a lens.
The focal length of a thin convex lens is ______ than that of a thick convex lens.
Study the diagram below.
what are the points O, O’ called?
List four properties of the image formed by a convex mirror.
(a) What type of a lens can be used as a magnifying glass?
(b) Show by a ray diagram the formation of a real image by simple magnifying lens.
State the position of object, position of image, nature of image when: Convex lens is used in observing biological specimens.
In sunglasses, both of its surfaces are curved, yet their behaviour is neither like a convex lens nor like a concave lens. State the reason.
How will you determine the focal length of a convex lens by the plane mirror method?
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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 `"𝑣"/"𝑢"` 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)
