Physics HL Option G (Ralph Cheng)

Consider an electric charge oscillating about a fixed position. It produces a varying electric field It produces a varying magnetic field (a moving charge is similar to a current) The two fields are perpendicular to each other

See Image for table.
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.

 Light passing from one medium to another is refracted.  Degree of refraction (refractive index) depends on wavelength  The differential refraction is called dispersion.

The index of refaction depends on wavelength and is smaller for, for example, red light. White light entering a prism splits into the clours of the rainbow in a phenomenon called dispersion. The index of refraction for red light is smaller than that for blue and so a red ray has a larger angle of refraction.

Transmission: EM radiation passing from one medium to another. Partially reflected Partially refracted Absorption: If the energy of the EM radiation matches the energy difference between electron levels, photons will be absorbed. Scattering of radiation: EM radiation interacts with molecules causing the electrons to oscillate producing radiation in all directions. Does not alter the incident radiation in any other way.

- the effect of the Earth’s atmosphere on incident EM radiation. - simple explanations for the blue colour of the sky, red sunsets or sunrises, - the effect of the ozone layers - effect of increased CO₂ in the atmosphere.

· monochromatic--light with a single wavelength · coherent--light made up of waves that are in phase with each other

Laser is a source of coherent light.

Basically, atoms are population inverted, therefore, more exist in the higher-energy level, thereby emitting light of a certain frequency i.e. laser. Normally electrons occupy lowest available energy levels. To produce laser light a large number of electrons are promoted to a higher energy level

• medical applications • communications • technology (bar-code scanners, laser disks) • industry (surveying, welding and machining metals, drilling tiny holes in metals) • production of CDs • reading and writing CDs, DVDs, etc.

1. *Principal axis Line through the focal point of a lens and the center of the lens. 2. *Focal point Location on the principal axis where parallel light rays converge after passing through the lens. 3. *Focal length Distance between the focal point and the center of the lens. 4. *Linear magnification The ratio of the height of the image to the height of the object.

1. *Power of a converging lens The reciprocal of the focal length of the lens 2. *Dioptre The unit of power for a converging lens: 1 dioptre = 1 m^-1

1. *Linear magnification The ratio of the height of the image to the height of the object.

See image.

1. *Real image Image formed when light rays actually converge on a location and can be projected onto a screen. 2. *Virtual image Image formed by light rays that only appear to converge on a location and cannot be projected onto a screen.