An illustration of a boy trying on a hat and looking at his reflection in the mirror.

Illustration of an ellipse, whose major axis is vertical, inscribed in a circle whose diameter is equal…

Illustration of 16 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of 2 concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration of 2 concentric congruent ellipses that are rotated about the center at 90°. The ellipses…

Illustration of 4 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of 8 concentric congruent ellipses that are rotated about the center at equal intervals…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Illustration of concentric ellipses, whose major axes are vertical, inscribed in a circle whose diameter…

Isosceles Triangle with a dotted vertical line that is a line of symmetry.

Letter A with a dotted vertical line that is a line of symmetry.

Letter B with a dotted horizontal line that is a line of symmetry.

"The focus of a concave mirror is the point where the rays are brought together by reflection." -Comstock…

"To explain this, let us suppose that the arrow a, is diminished by reflection from the convex surface,…

"Suppose the arrow a to be the object reflected b the mirror d c; the incident rays a, flowing from…

This statue of Narcissus a Greek Mythological hero who was renown for his beauty. In this statue, he…

Oval with dotted vertical and horizontal lines that are lines of symmetry.

"In order strictly to equalize a fixed light over the whole horizon, which could not possibly be done…

"In 1763, or at latest before 1777, parabolic reflectors were first used for lighthouse illumination…

"In 1763, or at latest before 1777, parabolic reflectors were first used for lighthouse illumination…

"It will be seen that the parabolic mirror a is at best but a very imperfect instrument, for even if…

"Cathetal prisms readily yield the phenomena of total reflection as shown, and are often used when light…

"From the surface of a plane mirror, parallel rays are reflected parallel; but the convex mirror causes…

"The angle, ABD, included between the direction of the moving body before it strikes the reflecting…

"Let S be the position of the spectator; O and B the position of distant objects. The rays O R and B…

"Here, of the rays S A, S B, and S C, only the ray S C meets the eye of the spectator D. The spot C,…

"Mirror A/B is only half of person C's height. C is able to view his entire body through such a small…

"Irregular reflection or diffusion results from the incidence of radiant energy upon an irregular surface,…

"Thus, if a sunbeam, passing through a small aperure in the window shutter a, be permitted to fall upon…

"The ray a, c, is the ray of incidence, and that from c, to d, is the ray or reflection. The angles…

"Regular reflection results from the incidence of radiant energy upon a polished surface. When a beam…

A polished surface of metal, or any other suitable material, applied for the purpose of reflecting rays…

"In order to produce, on the catoptric system, a fixed light showing all round the circle, a number…

"If again the light was to revolve, then a revolving chandelier was employed having a certain number…

Square with dotted vertical, horizontal, and diagonal lines that are lines of symmetry.

"Start a trough from A. At the moment of its reflection as a crest a B, start a crest at A as shown.…

"It is apparent that the auditor, in this case, must be placed in the centre from which the sound proceeds,…