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प्रश्न
A student obtained clear image of window grills on the screen. But the teacher told him to get the image of a tree far away, instead of window. To get a clear image, the lens must be ............................
विकल्प
moved towards the screen.
moved away from the screen.
moved behind the screen.
moved far away from the screen.
उत्तर
moved towards the screen.
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संबंधित प्रश्न
If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system ?
A converging lens of focal length 5 cm is placed at a distance of 20 cm from a screen. How far from the lens should an object be placed so as to form its real image on the screen?
If the image formed by a lens is always diminished and erect, what is the nature of the lens?
Copy and complete the diagram below to show what happens to the rays of light when they pass through the concave lens:
Fill in the following blank with suitable word:
Lenses refract light to form images: a..................... lens can form both real and virtual images, but a diverging lens forms only ...................... images.
Give the position, size and nature of image of formed by a concave lens when the object is placed:
anywhere between optical centre and infinity.
Give the position, size and nature of image of formed by a concave lens when the object is placed:
at infinity.
Which type of lens is
a diverging lens? Explain your answer with diagrams.
When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object.
What is the focal length of lens B?
When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object.
What is the nature of lens A?
A concave lens of 20 cm focal length forms an image 15 cm from the lens. Compute the object distance.
(a) Find the position and size of the virtual image formed when an object 2 cm tall is placed 20 cm from:
(i) a diverging lens of focal length 40 cm.
(ii) a converging lens of focal length 40 cm.
(b) Draw labelled ray diagrams to show the formation of images in case (i) and (ii) above (The diagrams may not be according to scale).
State whether the following statement is true or false:
Short-sightedness can be cured by using a concave lens.
A concave lens, if kept at a proper distance from an object, can form its real image.
Express power of a concave lens of focal length 50 cm with its sign.
When an object is kept within the focus of a concave mirror, an enlarged image is formed behind the mirror. This image is :
Define the term principal foci as applied to a concave lens. Illustrate your answer with the aid of proper diagrams. Show the focal length of the lens in the diagram.
In a reading glass what is the position of the object with respect to the concave lens used?
