Advertisements
Advertisements
Question
Options
40 cm
25 cm
`1/40` cm.
`1/25` cm
Advertisements
Solution
The power of a convex lens is 2.5 dioptres. Its focal length is 40 cm.
APPEARS IN
RELATED QUESTIONS
If you focus the image of a distant object, whose shape is given below, on a screen using a convex lens, the shape of the image of this object on the screen would be:
(a)
(b)
(c)
(d)
A beam of light travelling in air is incident of water. Draw a ray-diagram indicating the change in its path in water.
A ray of light travelling in air is incident on a parallel-sided glass slab (or rectangular glass slab). Draw a ray-diagram indicating the change in its path in glass.
For what position of an object a real, diminished image is formed by a convex lens?
Describe with the help of a ray diagram the nature, size and position of the image formed when an object is placed at infinity (considerable distance) in front of a convex lens. State three characteristics of the image so formed.
How could you find the focal length of a convex lens rapidly but approximately?
An object 2 cm tall is placed on the axis of a convex lens of focal length 5 cm at a distance of 10 m from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?
What type of images can a convex lens make?
What kind of lens can form:
an inverted diminished image?
An object is placed 20 cm from (a) a converging lens, and (b) a diverging lens, of focal length 15 cm. Calculate the image position and magnification in each case.
The given below figure shows an object OA and its image IB formed by a lens
. 
draw suitable rays to locate the lens and its focus.
A lens forms an inverted image of an object. Name the kind of lens.
A pin 2 cm long is placed 12 cm away from a convex lens at right angles to the principal axis. If the focal length of the lens is 20 cm, by scale drawing find the size of the image and its magnification.
What happens to the image formed by a convex lens if its lower part is blackened?
State the position of object, position of image, nature of image when: Convex lens is used in observing biological specimens.
Write the three characteristics of the image formed by a convex lens of focal length 20 cm for the object at distance (i) 10 cm, (ii) 30 cm, (iii) 40 cm, (iv) 60 cm from the lens.
Which lens can produce a real and inverted image of an object?
Draw a ray diagram to illustrate the determination of the focal length of a convex lens using an auxiliary plane mirror.
Define the principal focus of a convex lens.
How will you determine the focal length of a convex lens by the plane mirror method?
