Refraction At A Plane Surface Flashcards

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1
Q

What is optics
What are the branches?
Define

A

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

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2
Q

Define

Transparent opaque translucent bodies

A

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.

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3
Q

Define
Ray of light
Beam of light
Convergent divergent parallel beam

A

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

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4
Q

Define image

Real and virtual image differentiate

A

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

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5
Q

What is optical medium?

Homogenous. Heterogenous. Isotropic . anisotropic.

A

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

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6
Q

What is reflection?

Laws of reflection?

A

Reflection is the phenomenon in which light travelling in one medium incident on a surface of another returns to the medium

  1. The incident ray reflected ray and normal to the surface at the point of incidence all lie in the same plane
  2. The angle of incidence is equal to the angle of reflection.
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7
Q

Define refraction. Laws ?

A

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

  1. The incident ray reflected ray and normal to the surface at the point of incidence all lie in the same plane
  2. Snell’s law
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8
Q

State snell’s law

When is it not applicable?

A

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

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9
Q

Define angle of deviation

A

The difference between the angle of incidence and the angle of refraction
d = i ~ r

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10
Q

What is absolute refractive index

A

Refractive index of a medium wrt air or vacuum

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11
Q

Principle of reversibility

A

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

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12
Q

Define lateral shift. What factors affect it when is it zero

A
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.
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13
Q

What is normal shift ?

Factors?

A

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

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14
Q

Effects of refraction

A

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

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15
Q

Total internal reflection

Conditions

A

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

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16
Q

What is critical angle?

Factors

A

Critical angle for a pair of media is that angle of incidence in the denser medium for which angle of refraction is 90
Light just grazes the surface separating the two media

Refractive indexes of media
Wavelength

17
Q

Applications of optic fibre

A
  1. optical fibres are used in medical and optical examination. Doctors use different types of fibroscopes to visually examine inner part of stomach, intestine etc. this field of medicine is called endoscopy.
  2. They are used to measure the flow of blood in the heart
  3. They are used to measure refractive index of liquids.
  4. They are used to measure temperature pressure and flow of liquids
  5. Conical optic fibres are used to diminish or enlarge optical images.
  6. They are used to transmit and receive electrical signals , which are converted , to light by suitable transducers.
18
Q

How is refractive index related to

Wavelength

A

Inversely

19
Q

Lateral shift is maximum for _________ colour and minimum for ________

A

Violet

Red

20
Q

How is refractive index related to

Wavelength

A

Inversely

21
Q

Lateral shift is maximum for _________ colour and minimum for ________

A

Violet

Red