Science 8Name:______
Refraction by Rectangular Prisms
.
As the incident rays enter the dense medium (glass) they SLOW DOWN and bend CLOSER to the normal line.
As the incident rays leave the glass, they SPEED UP and bend AWAY from the normal line.
Refraction by Convex Lenses
Normal lines on a curved lens depend on the curve of the surface!
Both refracted rays inside the lens bend TOWARD the normal lines, closer to the centre. The rays are no longer parallel!
Both rays leaving the lens bend AWAY from the normal lines. The curvature makes these normal lines at different angles, so the rays are now going to cross!
Refraction Rule for a Converging Lens
Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the FOCAL POINT on the opposite side of the lens.In the reverse direction, light from the focal point will leave the lens PARALLEL to the principal axis.
Refraction by Concave Lenses
Both refracted rays inside the lens SLOW DOWN and bend TOWARD the normal lines, but away from the centre. The rays are no longer parallel!
Both rays leaving the lens SPEED UP and bend AWAY from the normal lines. The curvature makes these normal lines at different angles, so the rays are now diverging!
REAL images form when rays cross. Double concave lenses can never produce a real image, only a VIRTUAL image.
Imagine tracing the diverging rays backward. They seem to be coming from a single point. The focal point is before the lens.
Refraction Rules for a Diverging Lens
- Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel in line with the focal point (i.e., in a direction such that its extension will pass through the focal point).
- Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis.
Some material adapted from The Physics Classroom, “Image Formation by Lenses”
Science 8Name:______
Refraction by Rectangular Prisms
.
As the incident rays enter the dense medium (glass) they SLOW DOWN and bend CLOSER to the normal line.
As the incident rays leave the glass, they SPEED UP and bend AWAY from the normal line.
Refraction by Convex Lenses
Normal lines on a curved lens depend on the curve of the surface!
Both refracted rays inside the lens bend TOWARD the normal lines, closer to the centre. The rays are no longer parallel!
Both rays leaving the lens bend AWAY from the normal lines. The curvature makes these normal lines at different angles, so the rays are now going to cross!
Refraction Rule for a Converging Lens
Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens.In the reverse direction, light from the focal point will leave the lens parallel to the principal axis.
Refraction by Concave Lenses
Both refracted rays inside the lens SLOW DOWN and bend TOWARD the normal lines, but away from the centre. The rays are no longer parallel!
Both rays leaving the lens SPEED UP and bend AWAY from the normal lines. The curvature makes these normal lines at different angles, so the rays are now diverging!
REAL images form when rays cross. Double concave lenses can never produce a real image, only a VIRTUAL image.
Imagine tracing the diverging rays backward. They seem to be coming from a single point. The focal point is before the lens.
Refraction Rules for a Diverging Lens
- Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel in line with the focal point (i.e., in a direction such that its extension will pass through the focal point).
- Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis.
Some material adapted from The Physics Classroom, “Image Formation by Lenses”
Science 8Name:______
Refraction
When light slows down it bends ______the normal line.
When light speeds up it bends ______from the normal line.
Complete the following ray diagrams by showing estimated changes to the refracted ray (Toward or away from the normal line, by a lot or a little?).
Air WaterAirDiamond
normal linenormal line
Water Air Diamond Air
normal line normal line