Advertisements
Advertisements
प्रश्न
The focal length of a lens is negative. In this case, state the kind of lens.
उत्तर
The negative focal length of a lens indicates that it is a concave lens.
APPEARS IN
संबंधित प्रश्न
If the image formed by a lens for all positions of an object placed in front of it is always erect and diminished, what is the nature of this lens? Draw a ray diagram to justify your answer.
Where must the object be placed for the image formed by a converging lens to be:
real, inverted and larger than the object?
Where must the object be placed for the image formed by a converging lens to be:
virtual, upright and larger than the object?
Copy and complete the diagram below to show what happens to the rays of light when they pass through the concave lens:
Things always look small on viewing through a lens. What is the nature of the lens?
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 B?
The power of a concave lens is 10 D and that of a convex lens is 6 D. When these two lenses are placed in contact with each other, the power of their combination will be :
(a) +16 D
(b) +4 D
(c) −16 D
(d) −4 D
The power of a converging lens is 4.5 D and that of a diverging lens is 3 D. The power of this combination of lenses placed close together is :
(a) +1.5D
(b) +7.5D
(c) −7.5D
(d) −1.5D
Explain the working of an astronomical telescope using refraction of light.
A lens forms an image between the object and the lens. Name the lens.
