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प्रश्न
A small bulb is placed at the principal focus of a convex lens. When the bulb is switched on, the lens will produce
पर्याय
a convergent beam of light
a divergent beam of light
a parallel beam of light
a coloured beam of light
उत्तर
A convergent beam of light
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संबंधित प्रश्न
A lens forms an upright and diminished image of an object when the object is placed at its focal point. Name the lens and draw a ray diagram to show the image formation.
A lens forms an erect, magnified, and virtual image of an object. Draw a labelled ray diagram to show the image formation.
A converging lens forms the image of an object placed in front of it beyond 2F2 of the lens. Where is the object placed?
An object is placed at a distance of more than 40 cm from a convex lens of focal length 20 cm. The image formed is real, inverted and ______.
For the object placed between the optical centre and focus of a convex lens, the image is ______.
Where should an object be placed so that a real and inverted image of the same size is obtained by a convex lens?
Explain the rules for obtaining images formed by a convex lens with the help of ray diagram.
Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15 cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?
A student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under
Position of candle = 12.0 cm
Position of convex lens = 50.0 cm
Position of the screen = 88.0 cm
- What is the focal length of the convex lens?
- Where will the image be formed if he shifts the candle towards the lens at a position of 31.0 cm?
- What will be the nature of the image formed if he further shifts the candle towards the lens?
- Draw a ray diagram to show the formation of the image in case (iii) as said above.
Complete the following table based on image formation by convex lens:
| Position of Object | Position of Image | Nature of Image |
| At infinity | (a) ______ | Real and inverted and highly diminished image |
| Beyond 2F1 | (b) ______ | (c) ______ |
| At 2F1 | (d) ______ | Real, inverted, same size (as object) image |
| Between F1 and 2F1 | Beyond 2F2 | (e) ______ |
| At focus F1 | (f) ______ | Real, inverted and highly enlarged image |
