Question

The word KVPY is written on a board and viewed through different lenses such that board is at a distance beyond the focal length of the lens.
Ignoring magnification effects, consider the following statements.
(I) Image (i) has been viewed from the planar side of a plano-convex lens and image(ii) from the convex side of a plano-convex lens.
(II) Image (i) has been viewed from the concave side of a plano-concave lens and image (ii) from the convex side of a plano-convex lens.
(III) Image (i) has been viewed from the concave side of a plano-concave lens and image (ii) from the planar side of a plano-convex lens.
(IV) Image (i) has been viewed from the planar side of a plano-concave lens and image (ii) from the convex side of a plano-convex lens.
Which of the above statements are correct?

• A. All four
• B. Only (III)
• C. Only (IV)
• D. Only (II), (III) and (IV)

Answer 1

The correct option is D Only (II), (III) and (IV)

Please note that the word 'plano-' is used and the 'side of the lens from which the image is viewed' is mentioned only to make the question tricky.

They really don't matter.

The nature and position of the image depends only on the focal length of the lens and the position of the object.

Real image is the one which really exists and can be obtained on a screen.

Virtual image doesn't really exist and cannot be obtained on a screen. However, in some situations, when we look from the opposite side of the object, it appears to be present on the same side as that of the object. Such an illusion is known as a virtual image.

Remember one golden rule about any image in lenses and mirrors.

If there is only one device (mirror or lens) at a time, then

Real image is always inverted and virtual always erect.

Therefore (i) is virtual, and (ii) is real.

A convex lens can produce both type of images but, a concave produces only virtual.

(1)Thus (ii) has to viewed from a convex lens only.

A convex lens produces virtual image only if the object is within its focal length. Since it is mentioned that the object is beyond the focal length, (i) cannot be produced by a convex lens.

(2)Thus (i) has to viewed from a concave lens only.

Since conditions 1 and 2 fail only in the 1st statement, that is the only wrong statement.