AP Physics B / IB Physics
Objectives Chapter 22-23
AP Objectives
4. Students should understand the inverse-square law so they can calculate the intensity of light at a
given distance from a source of specified power and compare the intensity of light at different distances
from the source.
C. Geometrical Optics
I. Students should understand the principles of reflection and refraction so they can:
a) Determine how the speed and wavelength of light change when light passes from one medium into another.
b) Show on a diagram the directions of reflected and refracted rays.
c) Use Snell's Law to relate the directions of the incident ray and the refracted ray, and the indices of refraction of the media.
d) Identify conditions under which total internal reflection will occur.
2. Students should understand in image formation by plane spherical mirrors so they can:
a) Related the focal point spherical mirror to it’s center of curvature.
b) Given a diagram of a mirror with the focal point shown, locate by tracing the image of a real object and
determine whether the image is real or virtual, upright or inverted, enlarged or reduced in size.
3. Students should understand image formation by converging or diverging lenses so they can:
a) Determine whether the focal length of a lens is increased or decreased as a result of a change in the
curvature of its surfaces or in the index of refraction of the material of which the lens is made or the
medium in which it is immersed.
b) Determined by ray tracing the location of the image of a real object located inside or outside the focal
point of the lens, and state whether the resulting image is upright or inverted, real or virtual.
c) Use the thin lens equation to relate the object distance, image distance, and focal length for lens and
determine the image size in terms of the object size.
d) Analyze simple situations in which the image formed by one lens serves as the object for another lens.
2. Students should understand dispersion and the electromagnetic spectrum so they can:
a) Relate a variation of index of refraction with frequency to a variation in refraction.
b) Know the names associated with electromagnetic radiation and be able to arrange in order of increasing wavelength the following: visible light of various colors, ultraviolet light, infrared light, radio waves, x-rays, and gamma rays.
Objectives for IB Physics
4.2 Wave Properties (5h) Standard Level
Reflection, refraction and transmission of waves
4.2.2 State Huygens' principle.
4.2.3 Apply Huygens' principle to two-dimensional plane waves to show that the angle of incidence is
equal to the angle of reflection.
4.2.4 Explain refraction using Huygens' principle.
4.2.5 Derive, using Huygens' principle, Snell's law for refraction.
The concept of refractive index is not required but the ratio of speeds is expected.
4.2.6 State and apply Snell's law.
OPTION H OPTICS
H.I The Nature of Light
Speed of light
H1.1 Outline the electromagnetic nature of light.
It is sufficient for students to know that an oscillating electric charge produces sinusoidally varying electric and magnetic fields and that the energy of the oscillating charge is propagated by means of the varying fields. Students should know that electromagnetic waves are transverse
waves and can travel in a vacuum.
H.1.2 Describe the different regions of the electromagnetic spectrum.
Students should know the order of magnitude of the frequencies for the different regions, and should also be able to identify a possible source of the radiation in each region.
H.1.3 Outline an experiment that measures the speed of light in a vacuum.
No specific experiment is required, but Michelson's method involving a rotating mirror would be appropriate. Experimental details are not required. Students should be aware that the speed of light in vacuum is now a defined value in terms of which the meter is defined.
Dispersion
H.1.4 Describe the dispersion of white light by a prism.
Students should know that different colors disperse in order of decreasing frequencies and that the colors can combine to produce white light.
H.1.5 Explain the dispersion of white light by a prism in terms of the frequency dependence of refractive
index.
No quantitative discussion is required but students should know that the refractive index for glass is smaller for red light than it is for blue light.
Lasers
H.1.6 Identify laser light as a source of monochromatic, coherent light. Students should be able to explain
monochromatic and coherent. Chapter 28
H.1.7 Outline a laser application from technology, industry or medicine.
Possible examples include:
· technology (bar-code scanners, laser discs)
· industry (surveying, welding and machining metals, drilling tiny holes in metals)
· medicine (destroying tissue in small areas, attaching the retina, corneal correction, cauterizing lymph vessels and capillaries).
H.2 Reflection at a Plane Surface
Nature of reflection
H.2.1 Distinguish between reflection at a mirror and diffuse reflection. Define the terms normal, incident
ray, reflected ray.
H.2.2 Students should know that the ray is a line that is perpendicular to the wave fronts. They should
recognize geometric optics as a study in which the wave nature of light can be ignored.
H.2.3 State the law of reflection.
Formation of an image by reflection
H.2.4 Construct a ray diagram to determine the formation of an image by reflection at a plane surface.
H.2.5 Explain the difference between a real and a virtual image. Describe the nature of the image formed
by reflection.
H.3 Refraction at a Plane Interface (3h)
Snell's law and refractive index
H.3.1Define refractive index.
H.3.2 Solve problems involving Snell's law and refractive index.
Image formation
H.3.3 Describe the nature of the image formed by refraction at a plane surface.
H.3.4 Explain why when part of a stick is immersed in water it appears to be bent.
H.3.5 Explain why the apparent depth of a body immersed in a liquid is not its
actual depth.
H.3.6 Derive the formula connecting real depth, apparent depth and refractive index. Solve problems
involving refraction at a plane interface.
Critical angle
H.3.8 State that, in general, light will be partially transmitted and partially reflected at a boundary between
two media.
H.3.9 Describe the phenomenon of total internal reflection.
Students should understand the terms critical ray and critical angle.
H.3.10 Derive a relationship between the critical angle and the refractive indices of the media.
H.3.11 Solve problems involving total internal reflection.
H.3.12 Explain the view as seen by an underwater observer when looking at the water-air interface.
H.3.13 Describe the action of prismatic reflectors.
For example, periscopes or binoculars.
H.3.14 Discuss how a light ray is transmitted along the length of an optical fiber.
H.3.15 Outline the uses of optical fibers.
It is sufficient that students know how optical fibers are used in the transmission of data and in medicine (endoscopes).
H.4 Refraction by lenses ( 3 h )
Types of lenses
H.4.1Explain qualitatively, in terms of refraction, the converging and diverging action of lenses.
H.4.2 Identify whether a lens is converging or diverging.
Image formation
H.4.3 Define the terms principal axis, focal point, focal length, linear magnification.
H.4.4 Construct ray diagrams to locate images formed by lenses.
Students should appreciate that any other rays incident on the lens from the object will also be focused, and that the image will be formed even if some of the rays are blocked off.
H.4.5 Determine the nature of images formed by different types of lenses with different object-to-lens
separations.
H.4.6 Solve problems for a single lens and a combination of lenses using the thin lens equation.
Problems can be solved either by scale drawing or calculation. Students do not need to know the lens maker's formula.