Refraction at Spherical Surfaces and by Lenses

Which of the following can form diminished, virtual and erect image of your face

A converging lens of focal length 20 cm and diameter 5 cm is cut along the line AB. The part of the lens shown shaded in the diagram is now used to form an image of a point P placed 30 cm away from it on the line XY. Which is perpendicular to the plane of the lens. The image of P will be formed.

An object is placed in front of a thin convex lens of focal length 30 cm and a plane mirror is placed 15 cm behind the lens. If the final image of the object coincides with the object, the distance of the object from the lens is

A thin lens of focal length $f$and its aperture has a diameter $d$. It forms an image of intensity $I$. Now the central part of the aperture upto diameter $\frac{d}{2}$ is blocked by an opaque paper. The focal length and image intensity would change to

When the object is at distances u₁ and u₂ the images formed by the same lens are real and virtual respectively and of the same size. Then focal length of the lens is

A thin convex lens forms a real image of a certain object 'p' times its size. The size of real image becomes 'q' times that of object when the lens is moved nearer to the object by a distance 'a' find focal length of the lens?

An objective is kept at a distance of $16 \mathrm{cm}$ from a thin lens and the image formed is real. If the object is kept at a distance of $6 \mathrm{cm}$ from the same lens the image formed is virtual. If the size of the images formed are equal, then find the focal length of the lens?

Two thin lenses of power +6D and –2D are in contact. The focal length of the combination would be:

Two thin lenses of power $+4 \mathrm{D}$ and $-2 \mathrm{D}$ are in contact. The focal length of the combination?

Two lenses of powers $10 \mathrm{D}$ and $-5 \mathrm{D}$are placed in contact.

(i) Calculate the power of the new lens.

(ii) Where should an object be held from the lens, so as to obtain a virtual image of magnification $2$?

An eye specialist prescribes spectacles having a combination of convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. The power of this lens combination in diopters is

How myopia can ce corrected by concave lens?

The focal plane of a lens:

What is focal plane of a lens?

Optical centre of a lens is important because it enables us to see the object more clearly without _____.

Is optical centre and centre of curvature same?

Explain optical centre of a lens with the help of proper diagrams?

What do you mean by focal plane of a lens ?

Transparent medium bounded by two refracting surfaces in which at least one of these is curved is a property of:

Draw ray diagram to show the formation of image of an object which is kept at infinity from concave lens.