PHYS 251 Chapter Notes - Chapter 18.3: Optical Axis, Total Internal Reflection, Virtual Image

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coralcrab720

27 Sep 2016

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Document Summary

When light rays cross the boundary between air and glass part of the light is reflected and part of the light is refracted. Refraction: the transmission of light from one medium to another with a change is direction. The angle between the incident ray and the normal is the angle of incidence. The angle on the transmitted side, measured from the normal is the angle of refraction. Index of refraction (n) determines how much a light ray bends when crossing a boundary between two different media. When n > n light ray bends closer to the normal. When n < n light ray bends away from the normal. Total internal reflection: the ray is unable to refract through the boundary and 100% of it is reflected, occurs when the critical angle (c), this occurs when = 90 . *there is no critical angle and no total internal reflection when n > n .

Related Questions

1)A light ray is incident on a reflecting surface. If the light ray makes a 25° angle with respect to the normal to the surface, what is the exact angle (in degrees) made by the reflected ray relative to the normal?

2)The light ray that makes the angle θ1' is the refracted ray (true or false?)

3)True or False: The Law of Reflection can be used to show how an image appears behind a mirror and it can also be used to determine where the image will be located.

4) Snell's law is another name for the

law of dispersion

law of reflection

law of refraction

5) A light ray incident on a block of glass makes an incident angle of 50.0° with the normal to the surface. The refracted ray in the block makes a 26.8° with the normal. What is the index of refraction of the glass?

A light ray traveling from a higher index of refraction medium into a lower index of refraction medium (for example, from water into the air) would bend away from the normal to the medium surface. When the refracted ray is parallel to the boundary of the medium, θ2= 90°. The incident angle, θ1, becomes θc, called the

viridianchinchilla179

1. A light ray is incident on a reflecting surface. If the light ray makes a 25° angle with respect to the normal to the surface, what is the exact angle (in degrees) made by the reflected ray relative to the normal?

2. The light ray that makes the angle θ₁' is the refracted ray (true or false?)

3. True or False: The Law of Reflection can be used to show how an image appears behind a mirror and it can also be used to determine where the image will be located.

4. Snell's law is another name for the

law of dispersion
law of reflection
law of refraction

5. A light ray incident on a block of glass makes an incident angle of 50.0° with the normal to the surface. The refracted ray in the block makes an 26.8° with the normal. What is the index of refraction of the glass?

6. A light ray traveling from a higher index of refraction medium into a lower index of refraction medium (for example, from water into air) would bend away from the normal to the medium surface. When the refracted ray is parallel to the boundary of the medium, θ₂= 90°. The incident angle, θ₁, becomes θ_c, called the

cauchy angle
critical angle
conjugate angle
classic angle

pearchinchilla839

In Example 33.11, the water-glass interface is horizontal. If instead this interface were tilted 15.0° above the horizontal, with the right side higher than the left side, what would be the angle from the vertical of the ray in the glass? (The ray in the water still makes an angle of 60.0° with the vertical).

EXAMPLE 33.11: Reflection and refraction

In Fig 33.11, material a is water and material b is a glass with an index of refraction 1.52. If the incident ray makes an angle of 60.0° with the normal, find the directions of the reflected and refracted rays.

SOLUTION

IDENTIFY: This is a problem in geometric optics. We are given the incident angle and the index of refraction of each material, and we need to find the reflected and refracted angles.

SET-UP: Figure 33.11 shows the rays and angles for this situation. The target variables are the reflected angle θ_r and the refracted angle θ_b. Since n_b is greater than n_a, the refracted angle must be smaller than the incident angle θ_a; this is shown in the figure.

EXECUTE: According to Eq 33.2, the angle the reflected ray makes with the normal is the same as that of the incident ray so θ_r= θ_a=60.0°.

To find the direction of the refracted ray, we use Snell’s law, Eq 33.4, with n_a=1.33, n_b=1.42, and θ_a=60.0°. We find:

EVALUATE: The second material has a larger refractive index than the first, just like the situation shown in Fig 33.8a. Hence, the refracted ray is bent toward the normal as the wave slows down upon entering the second material and θ_b< θ_a.

Figure 33.11. Reflection and refraction of light passing from water to glass

Figure 33.8. Reflection and refraction in three cases. (a) Material b has a larger index of refraction than material a. (b) (a) Material b has a smaller index of refraction than material a. (c) The incident light ray is normal to the interface between the materials.