PHYS 2020 Final

Diverging lens / Convex mirror image characteristics and sign of focal length

virtual

upright

diminished

NEGATIVE focal length

Image distance is negative when:

image is virtual

Converging lens / Concave mirror: object between f and lens plane

virtual

upright

magnified

Converging lens / Concave mirror: object at f

no image formed

Converging lens / Concave mirror: object between f and C

real

inverted

magnified

Converging lens / Concave mirror: object at 2f (=C=R)

real

inverted

same size

Converging lens / Concave mirror: object beyond C

real

inverted

diminished

Converging lens ray diagram

R1: parallel → through focal point

R2: through focal point → parallel

R3: through origin

Diverging lens ray diagram

R1: parallel → as if going though focal point on SAME side

R2: as if going through focal point on OPPOSITE side → parallel

R3: through origin

Concave mirror ray diagram

R1: parallel → through focal point

R2: through focal point → parallel

R3: to origin → reflected at same angle

Convex mirror ray diagram

R1: parallel → as if going through focal point on OPPOSITE side

R2: as if going through focal point on OPPOSITE side → parallel

R3: to origin → reflected at same angle

Telescope lenses

long f objective

short f eyepiece

Microscope lenses

short f objective

long f eyepiece