Thursday, December 22, 2011
Refraction
Light waves are part of the EM wave spectrum. When moving through an optical medium (i.e. air, glass, etc. …), the E field of the wave excites the electrons within the medium, causing them to oscillate, as a result, the light wave slows down slightly due to the loss of some of its kinetic energy. Its new speed is always less than that of the speed of light in a vacuum (v<c). Materials are characterized by their ability to bend as well as slow down light, which is known as optical refractive index (n).
         c
     n = -
         v
          speed of light in a vacuum
       = ----------------------------
         speed of light in the medium
n = 1 in a vacuum
n = more than 1 in all other media
Refraction itself occurs when light passes across an interface between two media with different indices of refraction. As a general rule (which can be derived by Snell’s law below), light refracts towards the normal when passing to a medium with a higher refractive index, and away from the normal when moving to a medium of lower refractive index.
Snell’s Law:
n₁sinα = n₂sinβ
where n₁ is the refractive index of the first medium
Reflection
One of the properties of a boundary between optical media is that some of the light that’s approaching the interface at the angle of incidence (α) is reflected back into the first medium, while the rest continues on into the second medium at the angle of refraction (β).
Angle of incidence = Angle of Reflection

Refraction

Light waves are part of the EM wave spectrum. When moving through an optical medium (i.e. air, glass, etc. …), the E field of the wave excites the electrons within the medium, causing them to oscillate, as a result, the light wave slows down slightly due to the loss of some of its kinetic energy. Its new speed is always less than that of the speed of light in a vacuum (v<c). Materials are characterized by their ability to bend as well as slow down light, which is known as optical refractive index (n).

         c
     n = -
         v
          speed of light in a vacuum
       = ----------------------------
         speed of light in the medium
n = 1 in a vacuum
n = more than 1 in all other media

Refraction itself occurs when light passes across an interface between two media with different indices of refraction. As a general rule (which can be derived by Snell’s law below), light refracts towards the normal when passing to a medium with a higher refractive index, and away from the normal when moving to a medium of lower refractive index.

Snell’s Law:

n₁sinα = n₂sinβ

where n₁ is the refractive index of the first medium

Reflection

One of the properties of a boundary between optical media is that some of the light that’s approaching the interface at the angle of incidence (α) is reflected back into the first medium, while the rest continues on into the second medium at the angle of refraction (β).

Angle of incidence = Angle of Reflection

Saturday, July 9, 2011
PLANETARY ORBIT
To stay in orbit at a particular distance, a planet must move at a particular speed around the sun. If its speed is too low, it will spiral into the sun. If it&#8217;s too high, it will fly off its orbit and move away from the sun.
The further a planet is from the sun, the less its speed is as it moves around the sun. This is due to the force of gravity being weaker the further it is from the sun. Consequentially, the speed of the planet needs to be less than if it were closer to the sun or else it would fly off its orbit and move away from the sun.
The further a planet is from the sun, the longer it takes to make a complete orbit. This is because the circumference of its orbit is greater and it moves slower.

PLANETARY ORBIT

To stay in orbit at a particular distance, a planet must move at a particular speed around the sun. If its speed is too low, it will spiral into the sun. If it’s too high, it will fly off its orbit and move away from the sun.

The further a planet is from the sun, the less its speed is as it moves around the sun. This is due to the force of gravity being weaker the further it is from the sun. Consequentially, the speed of the planet needs to be less than if it were closer to the sun or else it would fly off its orbit and move away from the sun.

The further a planet is from the sun, the longer it takes to make a complete orbit. This is because the circumference of its orbit is greater and it moves slower.