Ray Diagrams for Mirrors and Lenses

We need to understand how they are constructed

How light travels from the star to our eyes Understand how lenses are combined with

other lenses Understand how lenses are combined with

mirrors Use refraction and reflection

Before we can work with telescopes

Mirrors first

mirror

F C object

F = focal pointC = center of curvature

Rules for a concave mirror diagram

mirror

FC

object

Any incident ray traveling parallel to the principal axis on the way to the mirror will pass through the focal point upon reflection.

Rules for a concave mirror diagram

mirror

FC

object

Any incident ray passing through the focal point on the way to the mirror will travel parallel to the principal axis upon reflection.

Image

Plane mirrors are always virtual Curved depend on position of object

Real or VIRTUAL

Real images are always formed on the same side of the mirror as the object.

REAL, the image of the object could be projected upon a sheet of paper.

Virtual form on the other side of the mirror Virtual cannot be projected

Real or VIRTUAL

We need to find◦L = location

◦O – orientation (inverted or upright)

◦S = size (magnified, reduced, same)

◦Type (real or virtual

L.O.S.T. ANALYSIS

Rules for a concave mirror diagram

•This diagram is formed when you put the ojbect BEYOND C• It produces a REAL IMAGE •This image is also SMALLER and INVERTED

Rules for a concave mirror diagram

•This image is formed when you put the object AT C• It produces a REAL IMAGE •This image is also EQUAL SIZE and INVERTED

Rules for a concave mirror diagram

•This image is formed when you put the object in front of F• It produces a Virtual IMAGE •This image is also Larger SIZE and Upright

Rules for a concave mirror diagram•This image is formed when you put the between F AND C

• It produces a REAL IMAGE

•This image is also Larger SIZE and INVERTED

Weird

When the object is located at the focal point, no image is formed. light rays from the same point on the object will reflect off the mirror and neither converge nor diverge. After reflecting, the light rays are traveling parallel to each other and do not result in the formation of an image.

Can you see me?

STOP!GO OUTSIDE AND LOOK

ATFOCAL POINTS!

We need to find◦ L = location◦ O – orientation (inverted or upright)◦ S = size (magnified, reduced, same)◦ Type (real or virtual

PRACTICE PROBLEMS WORK SHEETS

Practice problem 1L IN FRONT OF MIRROR

O INVERTED

S SMALLER

T REAL

Practice Problem 2L IN FRONT OF MIRROR at the image

O INVERTED

S SAME SIZE

T REAL

Practice problem 3L IN FRONT OF MIRROR BEHIND

OBJECT

O INVERTED

S LARGER

T REAL

Number 1