Light - Reflection and Refraction
Frequently Asked Questions
The law of reflection states that the angle of incidence is equal to the angle of reflection, and the incident ray, reflected ray, and the normal all lie in the same plane.
Regular reflection occurs on smooth surfaces and produces clear images, while diffused reflection occurs on rough surfaces, scattering light in all directions without forming a clear image.
It is the ratio of the speed of light in vacuum to its speed in a medium. It tells how much light bends when entering a medium.
Due to refraction, light bends when it moves from water to air, making the pencil appear bent or displaced at the surface.
Plane mirror – used in dressing mirrors; Concave mirror – used by dentists and in torches; Convex mirror – used in vehicle rear-view mirrors.
Refraction helps in lenses, spectacles, cameras, microscopes, rainbows, and apparent bending of submerged objects.
It is the distance between the pole (or optical center) and the focus where parallel rays of light converge or appear to diverge.
Mirror formula: \( \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \); Magnification formula: \( m = \frac{h_i}{h_o} = -\frac{v}{u} \).
When light travels from a denser to a rarer medium and the angle of incidence exceeds the critical angle, it reflects completely within the denser medium.
Real images are formed when rays actually meet and can be projected; virtual images are formed when rays appear to meet and cannot be projected.
Concave lenses correct myopia (short-sightedness), while convex lenses are used in magnifiers, cameras, and microscopes.
Stars twinkle due to atmospheric refraction of their light; planets do not because they are closer and appear as extended light sources.
The power of a lens (P) is the reciprocal of its focal length (f in meters): \( P = \frac{1}{f} \); its SI unit is the diopter (D).
The light ray refracts twice and emerges parallel to the original ray but is laterally displaced.
Distances measured against the direction of incident light are positive, and those measured along it are negative. All distances are measured from the pole or optical center.
