Advertisements
Advertisements
Question
The power of a lens is +2.0D. Its focal length should be :
Options
100 cm
50 cm
25 cm
40 cm
Advertisements
Solution
50 cm
Focal length `=1/"power"=1/2.0=0.5m=50cm`
APPEARS IN
RELATED QUESTIONS
State the power of a lens S.I. unit.
A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens
Consider two statements A and B given below:
A: real image is always inverted
B: virtual image is always erect
Out of these two statements:
The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power: A or B.
Name the physical quantity whose unit is dioptre.
The focal length of a convex lens is 25 cm. What is its power?
The focal length of a lens is +150 mm. What kind of lens is it and what is its power?
A combination of lenses for a camera contains two converging lenses of focal lengths 20 cm and 40 cm and a diverging lens of focal length 50 cm. Find the power and focal length of the combination.
A converging lens has a focal length of 50 cm. The power of this lens is:
Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see:
(1) a blurred image on the wall of the laboratory.
(2) an erect image of the tree on the lens.
(3) no image as the screen has been removed
(4) an inverted image of the tree at the focus of the lens.
A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?
A pin of length 2.00 cm is placed perpendicular to the principal axis of a converging lens. An inverted image of size 1.00 cm is formed at a distance of 40.0 cm from the pin. Find the focal length of the lens and its distance from the pin.
How is accommodation produced?
Which lens has more power a thick lens or a thin lens?
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
Complete the diagram to show the formation of the image of the object AB.
(i) Name the Lens LL’.
(ii) Where is the image of the object AB formed?
(iii) State three characteristics of the image.
Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of –50 cm. What is the nature of the lens and its power used by each of them?
The focal length of a double convex lens is equal to the radius of curvature of either surface. What is the refractive index of its material?
The deviation of the incident light rays produced by a lens on refraction through it is a measure of its:
