Refraction of Light at Plane Surfaces Flashcards
Define reflection of light.
The return of light in the same medium after striking a polished surface is called reflection of light.
Which 2 laws does reflection of light obey?
- The angle of incidence = angle of reflection
2. The incident ray, the normal, and the reflected ray all lie in one plane.
Light has the maximum speed in which medium? What is the speed?
Light has the maximum speed (=3*10^8 m s-1) in vacuum and it travels with different speeds in different media.
What is the speed of light in air?
3*10^8 m s-1
What is the speed of light in water?
2.25*10^8 m s-1
What is the speed of light in glass?
2*10^8 m s-1
When does the speed of light remain constant?
In a transparent homogeneous medium
When is a medium said to be optically denser?
When light passes from one medium to another and it slows down, the second medium is said to be optically denser than the first one. Similarly, if light speeds up in the second medium, it is said to be optically rarer than the first one.
What is the relation between optical density and density of a medium?
Optical density has no relation with the density of a medium. Optical density depends upon the speed of light in that medium, whereas the density of a medium depends on its inter-molecular separation.
Give an example of optical density not being dependent upon density.
Kerosene has a lesser density than water (as it floats on water), but it is optically denser than water.
What is reflected light?
When a ray of light travelling in a transparent medium strikes obliquely at the surface of another transparent medium, a part of light returns back into the first medium obeying the laws of reflection and is called the reflected light.
What is refracted light?
After reflection, the remaining part of light enters into the other medium and travels in a straight path but in a direction different from its initial direction and is called the refracted light.
At the boundary separating two media, light suffers __ and __
partial reflection , partial refraction
What is refraction?
The change in the direction of the path of light, when it passes from one transparent medium to another transparent medium, is called refraction.
What type of phenomenon is refraction?
The refraction of light is essentially a surface phenomenon.
What happens to the amplitude of the refracted light after reflection?
The amplitude (or intensity) of the refracted light will be less than that of the incident light because a part of the incident light has suffered reflection.
When does a ray of light bend towards the normal?
When it is travelling from an optically rarer to an optically denser medium.
What is the deviation for a ray of light travelling from a rarer to a denser medium?
i-r, because /_ r < /_ i
Define deviation.
Deviation means the angle through which the ray turns i.e., the angle between the direction of refracted ray and the direction of incident ray. It is denoted by the letter
When does a ray bend away from the normal?
When it travels from an optically denser to an optically rarer medium. The deviation is r-i
When does a ray of light pass undeviated?
When the ray of light is incident normally on the surface separating the two media. Deviation is 0.
What is the cause of refraction?
When a ray of light passes from one medium to another medium, refraction occurs because of the change in speed of light in going from one medium to another.
In which two cases does a ray of light pass undeviated from one medium to another?
- If the speed of light remains the same in passing from one medium to another.
- If the ray of light is incident normally on the surface of the second medium, its speed will change but direction will not.
Which scientist gave the two laws of refraction?
The Dutch scientist Willebrod Snell gave the laws of refraction, so they are known as Snell’s laws.
What are the 2 laws of refraction?
- The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.
- The ratio of the sine of the angle of incidence i to the sine of angle of refraction r is constant for the pair of given media, i.e., mathematically,
sin i/sin r= constant 1μ2
sin i/sin r= constant 1μ2. Here, what is the refractive index?
The constant 1μ2 is called the refractive index of the second medium with respect to the first medium.