thin converging lens (physics) Flashcards
what is a lens
piece of clear plastic or glass with curved surfaces for concentrating or dispersing light rays
types of lenses + description
converging: thinner in the middle vs edges
diverging: thicker in the middle vs edges
what is the principal axis
the line which passes through the centre of the lens and which is perpendicular to the plane of the lens
what is the optical centre
point on the principal axis that is the midpoint between the surfaces of the lens
what is the focal length
distance between the optical centre and the principal focus point
what is the principal focus point
the point on the principal axis where all the rays parallel to the principal axis meet after passing through the lens
what is the focal plane
the plane perpendicular to the principal axis on which all parallel rays meet after passing through the lens
what happens when the paralel beam of rays incident on a thin converging lens is not parallel to the principal axis
rays are refracted to a point on the focal plane
what are the 3 things to note abt converging lens
- thinner lens –> longer focal length
- refractive index increases –> longer focal length
- diameter increases –> focal length no change, brightness increase
characteristics of image when obj distance > 2f
- real
- inverted
- diminished
characteristics of image when obj distance =2f
- real
- inverted
- same size
characteristics of image when f < obj distance < 2f
- real
- inverted
- magnified
characteristics of image when obj distance = f
no image formed because rays don’t converge
characteristics of image when obj distance < f
- virtual
- upright
- magnified
characteristics of image when obj distance is rlly far
