Types of Converging Lenses

LIGHTWhere does light come from?

Where else does light come from?

How does light travel?Light rays travel in straight lines from the light source.When it hits an opaque object, some light is absorbed and the rest reflects off.If the object is transparent, light rays pass through it easily.If the object is translucent, some light can pass through, but the rest of the light will be reflected.lightsourceHow do we see?Light coming from, (or reflecting off) objects enters the eye through the cornea then the pupil.

It is focused clearly by the lens on to the retina.

The light sensitive cells of the retina gather information about patterns of light and dark, colour and movement and send it through the optic nerve.How do we see?Information entering the brain through the optic nerve, is then transmitted through more nerve pathways to the visual cortex.

Here the patterns of light and dark, colour and movement are interpreted.

The brain, based on past experience, can then understand what it sees.How do we see colour?Light from most light sources looks white, but actually contains all the colours of the spectrum; also known as the rainbow.If an object looks blue, it is absorbing every colour except blue, which is reflecting off it and entering your eyes.If an object looks orange, it is absorbing every colour except orange, which, again, is reflecting off and entering your eyes.If an object looks red... (You get the idea!)lightsourceHow does light reflect?Angle of incidenceAngle of reflectionThe angle of reflection is always equal to the angel of incidence.onoffLight can only be reflected in straight lines.onoffHow does light form shadows?Light rays travel in straight lines, radiating out from the light source.If rays are blocked by an opaque object a shadow forms where the light cannot reach.If the light source is moved closer to the object, more light is blocked and a larger shadow is formed. lightsourcelightsourceHow does sunlight cause shadows?6am8am9am12am2pm10am3pm4pm7pmLooking North, the Sun appears to rise in the East......and travel across the sky until it sets in the West.The position of the Sun effects the position and length of the shadows created.Thanks to this natural phenomenon a sundial is able to tell us the time, as long as it is a sunny day!DispersionDispersion is the event decomposition polychromatic light (white) to light-monochromatic light (me, ji, me, hi, bi, ni, u) on the prism through refraction or bending.

DiffractionDiffraction is the ability of light waves to bend around obstacles placed in their path.

PolarizationPolarization(alsopolarisation) is a property ofwaves that canoscillatewith more than one orientation.

RefractionRefractionis the change in direction of propagation of awavedue to a change in itstransmission medium.

ReflectionReflectionis the change in direction of awavefrontat aninterfacebetween two differentmediaso that the wavefront returns into the medium from which it originated.

LensIs a transparent object with at least one curved side that causes light to refract.Have 2 sidesEither side could be plane, concave or convex.We group them into two: converging lenses (where the light rays come together at a common point) and diverging (when light rays spread apart)17Types of Converging LensesIn order for a lens to converge light it must be thicker near the midpoint to allow more bending.

Double-convex lens

Plano-convex lens

Converging meniscus lens Types of Diverging LensesIn order for a lens to diverge light it must be thinner near the midpoint to allow more bending.Double-concave lens

Plano-concave lens

diverging meniscus lens

Image Construction:Ray 1: A ray parallel to lens axis passes through the far focus of a converging lens or appears to come from the near focus of a diverging lens.

Converging LensDiverging LensFRay 1FRay 1Image Construction:Ray 2: A ray passing through the near focal point of a converging lens or proceeding toward the far focal point of a diverging lens is refracted parallel to the lens axis.

Converging LensDiverging LensFRay 1FRay 1Ray 2Ray 2Image Construction:Ray 3: A ray passing through the center of any lens continues in a straight line. The refraction at the first surface is balanced by the refraction at the second surface.

Converging LensDiverging LensFRay 1FRay 1Ray 2Ray 2Ray 3Ray 3Object Outside 2F1. The image is inverted, i.e., opposite to the object orientation.2. The image is real, i.e., formed by actual light on the opposite side of the lens. 3. The image is diminished in size, i.e., smaller than the object.Image is located between F and 2F

FF2F2FReal; inverted; diminishedObject at 2F

FF2F2FReal; inverted; same size1. The image is inverted, i.e., opposite to the object orientation.2. The image is real, i.e., formed by actual light on the opposite side of lens. 3. The image is the same size as the object.Image is located at 2F on other sideObject Between 2F and F

FF2F2FReal; inverted; enlarged1. The image is inverted, i.e., opposite to the object orientation.2. The image is real; formed by actual light rays on opposite side3. The image is enlarged in size, i.e., larger than the object.Image is located beyond 2FObject at Focal Length F

FF2F2FWhen the object is located at the focal length, the rays of light are parallel. The lines never cross, and no image is formed.Parallel rays; no image formedObject Inside F

FF2F2FVirtual; erect; enlarged1. The image is erect, i.e., same orientation as the object.2. The image is virtual, i.e., formed where light does NOT go. 3. The image is enlarged in size, i.e., larger than the object.Image is located on near side of lensReview of Image FormationsObject Outside 2F Region

FF2F2FReal; inverted; diminished

FF2F2FReal; inverted; same size

FF2F2FReal; inverted; enlarged

FF2F2FParallel rays; no image formed

FF2F2FVirtual; erect; enlargedDiverging Lens Imaging

Diverging LensF

Diverging LensFAll images formed by diverging lenses are erect, virtual, and diminished. Images get larger as object approaches.