light 🕯 Flashcards
what are the laws of reflection?
1) incident ray, reflected ray and normal at the point of incidence all lie on the same plane
2) angle of incidence is equal to the angle of reflection
what is refraction?
refraction is the bending of light as it passes from one optical medium to another
what is refractive index?
refractive index is the ratio of the speed of light in the vacuum to the speed of light in the medium
formulae involving refractive index (x3)
1) n = c / v
2) n = sin air / sin not air (snells law)
3) n = 1 / sin c
what is critical angle?
the angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 90 degrees
what is total internal reflection?
total internal reflection is the complete reflection of a light ray inside an optically denser medium at its boundary with an optically less dense medium
what is the focal point of a lens?
the point at which all light rays parallel to the principle axis converge after being refracted by the lens
when object at infinity, image…
real, inverted, diminished at F (teloscope)
when object between 2F and infinity, image…
real, inverted, diminished between F and 2F (camera)
when object at 2F, image…
real, inverted, same size at 2F (photocopier making same size copies)
when object between F and 2F, image…
real, inverted between 2F and infinity (projector)
when object at F. image…
same side as object, at infinity (spotlight)
when object between F and optical centre, image…
virtual, upright and magnified (magnifying glass)
