Found 2 items, similar to Virtual image.
English → English
Definition: virtual image
n : a reflected optical image (as seen in a plane mirror)
English → English
Definition: Virtual image
([i^]m"[asl]j; 48), n. [F., fr. L. imago,
imaginis, from the root of imitari to imitate. See Imitate
and cf. Imagine
1. An imitation, representation, or similitude of any person,
thing, or act, sculptured, drawn, painted, or otherwise
made perceptible to the sight; a visible presentation; a
copy; a likeness; an effigy; a picture; a semblance.
Even like a stony image, cold and numb. --Shak.
Whose is this image and superscription? --Matt.
This play is the image of a murder done in Vienna.
And God created man in his own image. --Gen. i. 27.
2. Hence: The likeness of anything to which worship is paid;
an idol. --Chaucer.
Thou shalt not make unto thee any graven image, . .
. thou shalt not bow down thyself to them. --Ex. xx.
3. Show; appearance; cast.
The face of things a frightful image bears.
4. A representation of anything to the mind; a picture drawn
by the fancy; a conception; an idea.
Can we conceive
Image of aught delightful, soft, or great? --Prior.
5. (Rhet.) A picture, example, or illustration, often taken
from sensible objects, and used to illustrate a subject;
usually, an extended metaphor. --Brande & C.
6. (Opt.) The figure or picture of any object formed at the
focus of a lens or mirror, by rays of light from the
several points of the object symmetrically refracted or
reflected to corresponding points in such focus; this may
be received on a screen, a photographic plate, or the
retina of the eye, and viewed directly by the eye, or with
an eyeglass, as in the telescope and microscope; the
likeness of an object formed by reflection; as, to see
one's image in a mirror.
. See under Electrical
, one who destroys images; an iconoclast.
, Image maker
, a sculptor.
, the worship of images as symbols; iconolatry
distinguished from idolatry; the worship of images
(Physics), the image of the retinal blood
vessels projected in, not merely on, that membrane.
(Optics), a point or system of points, on one
side of a mirror or lens, which, if it existed, would emit
the system of rays which actually exists on the other side
of the mirror or lens. --Clerk Maxwell.
(?; 135), a. [Cf. F. virtuel. See Virtue
1. Having the power of acting or of invisible efficacy
without the agency of the material or sensible part;
Heat and cold have a virtual transition, without
communication of substance. --Bacon.
Every kind that lives,
Fomented by his virtual power, and warmed. --Milton.
2. Being in essence or effect, not in fact; as, the virtual
presence of a man in his agent or substitute.
A thing has a virtual existence when it has all the
conditions necessary to its actual existence.
To mask by slight differences in the manners a
virtual identity in the substance. --De Quincey.
Principle of virtual velocities
(Mech.), the law that when
several forces are in equilibrium, the algebraic sum of
their virtual moments is equal to zero.
(Opt.), the point from which rays, having
been rendered divergent by reflection of refraction,
appear to issue; the point at which converging rays would
meet if not reflected or refracted before they reach it.
. (Optics) See under Image
(of a force) (Mech.), the product of the
intensity of the force multiplied by the virtual velocity
of its point of application; -- sometimes called virtual work
(Mech.), a minute hypothetical
displacement, assumed in analysis to facilitate the
investigation of statical problems. With respect to any
given force of a number of forces holding a material
system in equilibrium, it is the projection, upon the
direction of the force, of a line joining its point of
application with a new position of that point indefinitely
near to the first, to which the point is conceived to have
been moved, without disturbing the equilibrium of the
system, or the connections of its parts with each other.
Strictly speaking, it is not a velocity but a length.
. (Mech.) See Virtual moment