Question

The image of an object formed by a device is always virtual and small. The device may be:
(A) glass plate
(B) concave lens
(C) convex lens
(D) concave mirror

Answer 1

Hint: We should use the knowledge about images. Thus, we can say that virtual images are images that are formed in locations where light does not actually reach. Light does not actually pass through the location on the other side of the mirror; it only appears to an observer as though the light is coming from this location. A real image occurs where rays converge, whereas a virtual image occurs where rays only appear to diverge. Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted.

Complete step by step answer
Let us define each of the options to get the basic idea about the right answer:
In option A we have a glass plate which produces no image as the light rays incident upon a glass plate undergo refraction.
In option B we have a concave lens which always produces virtual, erect and diminished images and the decrease in the size of the image depends on the position of the object.
In the option C we have a convex lens which produces real and virtual, erect and inverted, diminished, same-sized and magnified images depending upon the position of the object on the principal axis.
In the option D we have concave mirrors which produce real and virtual, erect and inverted, diminished, same-sized and magnified images depending upon the position of the object on the principal axis.

Hence, the correct answer is OPTION B.

Note: We conclude that in physics, refraction is the change in direction of a wave passing from one medium to another or from a gradual change in the medium. Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction. Refraction is an effect that occurs when a light wave, incident at an angle away from the normal, passes a boundary from one medium into another in which there is a change in velocity of the light. The wavelength decreases as the light enters the medium and the light wave changes direction.
Let us know the laws of reflection. Laws of refraction state that: The incident ray, reflected ray and the normal, to the interface of any two given mediums; all lie in the same plane. The ratio of the sine of the angle of incidence and sine of the angle of refraction is constant.