Ray Optics and Optical Instruments Mind Map

Reflection at a spherical mirror is the change in direction of light after striking a concave or convex reflecting surface that is part of a sphere, forming images according to the laws of reflection and the mirror formula.

Before using the formula, draw a small axis sketch and mark the signs of u, v and f. This prevents most mirror numerical errors.

Refraction is the bending of light when it passes obliquely from one transparent medium to another because its speed changes. Total internal reflection is the complete reflection of light back into a denser medium when the angle of incidence exceeds the critical angle.

For TIR questions, check the direction of travel first. If light is going from rarer to denser medium, TIR cannot occur.

Refraction at a spherical surface describes image formation when light passes between two media separated by a curved refracting boundary. The lens maker's formula gives the focal length of a thin lens in terms of refractive index and radii of curvature of its two surfaces.

In lens maker problems, first write the direction of incident light and decide the signs of R1 and R2 from the position of each centre of curvature.

Power of a lens is the measure of its ability to converge or diverge light, numerically equal to the reciprocal of focal length in metres.

Convert cm to m before using P = 1/f. Then keep the sign of focal length, because the sign tells whether the lens is converging or diverging.

A prism deviates light because refraction occurs at two inclined surfaces. Dispersion is the splitting of white light into its constituent colours because refractive index depends on wavelength.

In prism diagrams, mark the base direction and remember that deviation is towards the base, while violet bends more than red in glass.

Optical instruments use lenses or mirrors to increase the apparent size or resolving usefulness of objects. A microscope magnifies nearby small objects, while a telescope increases the angular size of distant objects.

For instrument questions, identify final image position first: near point gives larger magnifying power but more eye strain; final image at infinity is comfortable viewing.