Refraction At A Plane Surface Flashcards
What is optics
What are the branches?
Define
The branch of physics which deals with the nature properties sources and effects of light is optics
Broadly classified into
1. Physical optics which deals with the study of wave nature of light and it’s interactions with matter.
2. Geometrical optics which deals with the study of simple properties of light and optical instruments assuming that light travels in straight lines ray concept is used
Define
Transparent opaque translucent bodies
Transparent bodies are those substances which allow most of the light incident on them to pass through them
Opaque bodies are those substances which don’t allow most of the light incident on them to pass through them
Translucent bodies are those which allow only a fraction of the light incident on them through them.
Define
Ray of light
Beam of light
Convergent divergent parallel beam
Ray of light is a straight line which represents the direction of propagation of light
Beam of light is a collection of rays
Convergent beam is one where the rays meet or tend to meet at a point
Divergent beam is one where the rays diverge or appear to diverge from a point
Parallel beam is one where the rays of light are parallel
Define image
Real and virtual image differentiate
Rays of light coming from a point after reflection refraction or both appear to diverge from a point or converge this point is the image
If the rays converge image is real. Can be caught on screen. Inverted
Virtual appear to diverge erect cant be caught on screen
What is optical medium?
Homogenous. Heterogenous. Isotropic . anisotropic.
An optical medium is one which allows incident light to pass through it. It may or may not be composed of matter.
An optical medium if it consists of matter is homogenous if its density is the same at all points otherwise heterogenous
It is Isotropic is speed of light is same in all directions like glass. Otherwise anisotropic like quartz
What is reflection?
Laws of reflection?
Reflection is the phenomenon in which light travelling in one medium incident on a surface of another returns to the medium
- The incident ray reflected ray and normal to the surface at the point of incidence all lie in the same plane
- The angle of incidence is equal to the angle of reflection.
Define refraction. Laws ?
The phenomenon in which there is change in the speed of light as it travels from 1 medium to another and the consequent bending of the ray of light incident obliquely at the surface of separation of the two media
- The incident ray reflected ray and normal to the surface at the point of incidence all lie in the same plane
- Snell’s law
State snell’s law
When is it not applicable?
For a given pair of media and light of given wavelength , ratio of the sine of the angle of incidence to the sine of the angle of refraction is always a constant
Not applicable when angle is 90 or for normal incidence
Define angle of deviation
The difference between the angle of incidence and the angle of refraction
d = i ~ r
What is absolute refractive index
Refractive index of a medium wrt air or vacuum
Principle of reversibility
If a ray of light from a source after undergoing any number of reflections and/or refractions has its path reversed at any stage then it travels back to the source along the same path in the opposite direction
Define lateral shift. What factors affect it when is it zero
The perpendicular distance between the emergent ray and incident ray direction is called the lateral shift Depends on 1. Thickness of slab. 2. Wavelength of light 3. Refractive index of the media 4 angle of incidence It is zero for normal incidence.
What is normal shift ?
Factors?
The apparent shift in position of the object measured along the normal to the surface of separation
Factors
1. Distance of object from refracting surface
2. Refractive index of medium in which object is
3. Refractive index of medium from where it is viewed
4. Wavelength of illuminating light
Independent of position of object below refracting medium
Effects of refraction
Bending of stick immersed in water
Coin in bucket of water appears raised
Sun is visible before sunrise and after sunset due to atmospheric refraction
Total internal reflection
Conditions
It is the phenomenon where complete reflection of light back into the medium occurs for angle greater than the critical angle
1. Light travel from optically denser to rarer medium
Angle of incidence in the optically denser medium must be greater than the critical angle
