List of top Physics Questions on spherical lenses

What is the focal length of a lens if its power is +2 D?
A convex lens has a focal length of 10 cm. What is the magnification produced when the object is placed 30 cm from the lens?
A convex lens has a focal length of \( 20 \, \text{cm} \). An object is placed at a distance of \( 30 \, \text{cm} \) from the lens. What is the position of the image formed?
An object is placed in front of a convex lens of focal length 12 cm. If the size of the real image formed is half the size of the object, then the distance of the object from the lens is:
Radius of curvature of equiconvex lens is 20 cm. Material of lens is having refractive index of 1.5. Find image distance from lens if an object is placed 10 cm away from the lens.
A biconvex lens of refractive index 1.5 has a focal length of 20 cm in air. Its focal length when immersed in a liquid of refractive index 1.6 will be:
A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is :
For an object placed at a distance $24\, m$ from a lens, a sharp focused image is observed on a screen placed at a distance $12\, cm$ from the lens A glass plate of refractive index $15$ and thickness $1 \,cm$ is introduced between lens and screen such that the glass plate plane faces parallel to the screen By what distance should the object be shifted so that a sharp focused image is observed again on the screen?

Two objects \(A\) and \(B\)are placed at \(15\, cm\) and \(25\, cm\) from the pole in front of a concave mirros having radius of curvature \(40\, cm\). The distance between images formed by the mirror is:

A point object, 'O' is placed in front of two thin symmetrical coaxial convex lenses L1 and L2 with focal length 24 cm and 9 cm respectively. The distance between two lenses is 10 cm and the object is placed 6 cm away from lens L1 as shown in the figure. The distance between the object and the image formed by the system of two lenses is _____ cm.
two thin symmetrical coaxial convex lenses L1 and L2 with focal length

Two convex lenses of focal length 20 cm each are placed coaxially with a separation of 60 cm between them. The image of the distant object formed by the combination is at cm from the first lens.

Two identical thin biconvex lenses of focal length 15 cm and refractive index 1.5 are in contact with each other. The space between the lenses is filled with a liquid of refractive index 1.25. The focal length of the combination is ___ cm.

A convex lens has power P. It is cut into two halves along its principal axis. Further one piece (out of the two halves) is cut into two halves perpendicular to the principal axis . Choose the incorrect option for the reported pieces.

Two plano-convex lenses (1 and 2) of glass of refractive index 1.5 have radii of curvature 25cm and 20cm. They are placed in contact with their curved surfaces towards each other and the space between them is filled with liquid of refractive index 4/3. The combination is: 

A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2 in the central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively:
A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2 in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively:

The given lens is broken into four parts and rearranged as shown. If the initial focal length is \( f \), then after rearrangement the equivalent focal length is â

The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is $40\, cm$. The area of the image is $9$ times that of the square. The focal length of the lens is :