Optics Terminology

Focal point

The point to which photons of light either converge to (converging lens or mirror) or appear to diverge away from (diverging lens or mirror):

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Focal-length.svg/360px-Focal-length.svg.png

Optical element

A lens or a mirror

A converging lens does what to parallel light?

Bends it towards the focal point

A diverging lens does what to parallel light?

Bends it in a way that it seems to emanate from a focal point

A converging lens is _________ in the middle than at the edges

Thicker

A diverging lens is ________ in the middle than at the edges

Thinner

The focal length of a converging optical element is

Positive

The focal length of a diverging optical element is

Negative

How many focal points does a lens have?

Two

How many focal points does a mirror have?

One

An inverted image is ______________ with respect to the object

Upside-down

An erect image is ________________ with respect to the object

Right-side-up

The point where the optical axis meets the optical element is called the _________________

Vertex

The object is on the same side as the incoming light, the object distance is

Positive

The image is on the same side as the outgoing light, the image distance is

Positive

The image is NOT on the same side as the outgoing light, the image distance is

Negative

The sign of the object height is

Always positive

The sign of the image height is

Positive if erect, negative if inverted

Magnification is

Image height over object height (unit-less!)