Advertisements
Advertisements
प्रश्न
The power of a lens is + 0.2 D. Calculate its focal length.
उत्तर
Power of a lens is given by:
Power (P) =`1/f`
`f=1/p`
`f=1/0.2=5m`
APPEARS IN
संबंधित प्रश्न
Calculate the focal length of a corrective lens having power +2D.
Find the focal length of a lens of power −2.0 D. What type of lens is this?
(a) At what distance should the lens be held from the figure in order to view the squares distinctly with the maximum possible magnifying power?
(b) What is the magnification in this case?
(c) Is the magnification equal to the magnifying power in this case? Explain.
Which has more power : a thick convex lens or a thin convex lens, made of the same glass? Give reason for your choice.
The optician's prescription for a spectacle lens is marked +0.5 D. What is the:
(a) nature of spectacle lens?
(b) focal length of spectacle lens?
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
A symmetric double convex lens in cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power a cut-lens will be
Consider three converging lenses L1, L2 and L3 having identical geometrical construction. The index of refraction of L1 and L2 are \[\mu_1 \text{ and } \mu_2\] respectively. The upper half of the lens L3 has a refractive index \[\mu_1\] and the lower half has \[\mu_2\] following figure . A point object O is imaged at O1 by the lens L1 and at O2 by the lens L2placed in same position. If L3 is placed at the same place,
(a) there will be an image at O1
(b) there will be an image at O2.
(c) the only image will form somewhere between O1 and O2
(d) the only image will form away from O2.
The following diagram shows the object O and the image I formed by a lens. Copy the diagram and on it mark the positions of the lens LL’ and focus (F). Name the lens.
An object is kept at a distance of 1m from a lens of power +2D:
- Identify the type of lens.
- Calculate its focal length and distance of the image formed.
