<![CDATA[]]> true true true false true DESCRIPTION_EDITOR Refraction - Snell's Law true

Snell's Law

This simulation illustrates Snell's Law.

Snell's Law states that light, when it passes from one medium to another, obeys the relationship:

n₁ sin(θ₁) = n₂ sin(θ₂)

n₁is the index of refraction of medium 1,

n₂is the index of refraction of medium 2,

θ₁is the angle, in medium 1, the light ray makes with the normal,

θ₂is the angle, in medium 2, the light ray makes with the normal.

The normal is the line perpendicular to the interface that passes through the interface at the same location the light does. In this simulation, the normal is a vertical line.

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Activities

The positions of the points on the screen are specified in meters - if you right-click on any point on the screen, the coordinates of that point will show up in yellow in the bottom left of medium 2 (the lower medium).

When you first start the simulation, the light source is the red point in medium 1. Drag the red point around the screen to change the angle of incidence (the angle the light incident on the interface between the two media makes with the normal to the interface, which is the vertical line). When the light strikes the interface, it generally splits into two rays, a reflected ray, which stays in the original medium, and a refracted ray, which passes into the other medium. What determines the direction of the reflected ray? What determines the direction of the refracted ray?
Use the sliders to adjust the index of refraction of each medium. How do the values of the indices of refraction affect the reflected ray? How do they affect the refracted ray?
There are two ways that you can get light to pass from one medium into another medium without changing direction. What are they?
Make a prediction regarding this situation. First, start the light off in medium 1. Move the purple point, in medium 2, so that the refracted ray passes through it. If you hit the button so that the light now starts in medium 2, from the purple point, will it pass through the red point, in medium 1? Justify your prediction, and then use the simulation to see if you are correct.
Under some conditions, none of the light incident on the boundary will pass through to the second medium. What is this phenomenon known as? Under what conditions will it occur?

]]> 25 1 false VARIABLE_EDITOR variables true VARIABLE_EDITOR calculations true VARIABLE_EDITOR color variables true VARIABLE_EDITOR StartandEnd true CODE_EDITOR Init Page true CODE_EDITOR FixRel Page true

 1.0)
  {
    refractFlag = false;
  }
else
  {
    refractFlag = true;
    xvalRefract = d2*sintheta2;
    yvalRefract = Math.sqrt(d2*d2-xvalRefract*xvalRefract);
    if (oneFlag)
    {
      yvalRefract = -yvalRefract;
    }
  }
  
if (oneFlag)
{
  theta1 = thetaStart;
  theta2 = thetaEnd;
}
else
{
  theta2 = thetaStart;
  theta1 = thetaEnd;
}

sinthetaCrit = Math.min(n1,n2)/Math.max(n1,n2);
xCrit = d2*sinthetaCrit;
yCrit = Math.sqrt(d2*d2-xCrit*xCrit);
if (n2 > n1)
{
  yCrit = -yCrit;
}

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