Advertisements
Advertisements
Question
Define the term focal length of a lens.
Solution
The distance from the optical centre O of the lens to its second focal point is called the focal length of the lens.
APPEARS IN
RELATED QUESTIONS
You have two lenses A and B of focal lengths +10 cm and –10 cm, respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8 cm from the lens? Draw a ray diagram to justify your answer
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
The focal length of a lens is +150 mm. What kind of lens is it and what is its power?
What do you understand by the power of a lens? Name one factor on which the power of a lens depends.
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
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
If the lens is of focal length 25 cm. Calculate the power of the lens.
Match the following:
| Column - I | Column - II | ||
| 1 | Retina | a | Path way of light |
| 2 | Pupil | b | Far point comes closer |
| 3 | Ciliary muscles | c | near point moves away |
| 4 | Myopia | d | Screen of the eye |
| 5 | Hypermetropia | e | Power of accommodation |
A convex lens with radii of curvature R1 = R2 is immersed in water. Assuming that the refractive indices of glass and water are 3/2 and 4/3 respectively, its focal length f1 in comparison to that in air, f, is ______.
A point object is placed at O in front of a glass sphere as shown in figure.
Show the formation of the image by the sphere.
