you need
- - pencil;
- - line;
- - protractor;
- - optical formula.
Guide
1
Make an explanatory drawing to a problem or a redraw in this condition.Just define a perpendicular, drawn to the boundary between two media at the point of incidence.Note the angles of incidence and refraction.This will help in solving problems on the density of the medium.
2
Learn the basic formula: 1 / d ± 1 / f = ± 1 / F;D = 1 / F;sinα / sinβ = n1 / n2;G = H / h = f / d.It happens that for the successful solution of the problem necessary to substitute these values only in one formula.d - the distance from the object to the lens, f - the distance from the lens to the
image, F - the distance from the optical center O to focus F;D - optical power of the lens;G - linear increase in the lens, H - height image, h - the height of the object;α - the angle of incidence, β - the angle of refraction, n - the relative refractive index of the medium.
3
for typical applications with a pond or vessel use in the construction of right-angled triangles of light rays.In the case of a reservoir depth of the leg will be drawn perpendicular to the bottom of the reservoir (H), the hypotenuse - a ray of light.In the second - hand have legs of the vessel perpendicular to each other, the hypotenuse - a ray of light.Draw perpendiculars, if the parties or the depth is not enough.
4
Apply properties adjacent and parallel angles to find any angle resulting triangle.Use the trigonometric function tangent to express one of the variables, or finding one of the legs.Tangent - the ratio of the opposite to the adjacent side.If the angles of incidence α and β are small refractive index, the tangents of these angles can be replaced by sines same angles.Relationship sinuses is equal to the ratio of the refractive indices in the media according to the above formula.
5
If the task is to construct, the first swipe main optical axis (GO), indicate the optical center (O), select the scale of the focus (F) on either side of O, selectas dual focus (2F).The conditions must be for the location of the object in front of the lens - between F and G, between F and 2F, for 2F and so on.
6
Build object in the form of arrows perpendicular g.o.o.From the end of the arrow draw two lines - one of them must be parallel g.o.o.and pass through F, the second - to pass through O. The lines can be crossed.From the point of intersection perpendicular to spend g.o.o.The image was obtained.The decision, in addition to constructing describe it - increase / decrease / equal;real / imaginary, inverted / direct.
7
the solution of problems on the diffraction grating use formula dsinφ = kλ, where d - period grating (slit width), φ - diffraction angle (the angle between the secondary waves and the incident beam perpendicular to the screen), k- number (order) minimum, λ - wavelength.
Note
Do not forget that the angles of diffraction spectra at imposing on each other should be equal.
Helpful Hint
The prism refracted light beam is deflected in the base of the prism.
Remember - if the angle of incidence equals the angle of reflection, the environment in which the reflected beam is optically denser (UBP);if the angle of incidence larger than the angle of refraction, the light passes from the OMP (lower optical density) of the medium in SSB, and vice versa.
Remember - if the angle of incidence equals the angle of reflection, the environment in which the reflected beam is optically denser (UBP);if the angle of incidence larger than the angle of refraction, the light passes from the OMP (lower optical density) of the medium in SSB, and vice versa.
Sources:
- 12th grade.Tasks.Light waves
- problem solving in optics