Chapter 6: Light and Optics Flashcards
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What is refraction?
Refraction is the bending of light as it passes from one medium to another. This happens because light travels at different speeds in different mediums.
What is the refractive index?
The refractive index of a medium is a measure of how much light bends when it enters that medium from a vacuum. It’s defined as the ratio of the speed of light in a vacuum to the speed of light in the medium.
What is Snell’s Law?
Snell’s Law describes the relationship between the angle of incidence (i), the angle of refraction (r), and the refractive indices (n) of the two mediums:
n₁ sin θ₁ = n₂ sin θ₂
What is total internal reflection?
Total internal reflection occurs when light travels from a medium of higher optical density to a medium of lower optical density, and the angle of incidence is greater than the critical angle. The light is reflected back into the first medium.
What is the critical angle?
The critical angle is the angle of incidence at which the refracted ray travels along the boundary between the two mediums (angle of refraction = 90 degrees). If the angle of incidence is greater than the critical angle, total internal reflection occurs.
What is a lens?
A lens is a piece of transparent material (like glass or plastic) that has at least one curved surface. Lenses can be convex (thicker in the middle) or concave (thinner in the middle).
What is the difference between a convex lens and a concave lens?
Convex lens: A converging lens that causes parallel rays of light to converge at a focal point.
Concave lens: A diverging lens that causes parallel rays of light to diverge as if they originated from a focal point.
What is the thin lens formula?
The thin lens formula relates the object distance (u), image distance (v), and focal length (f) of a lens:
1/f = 1/u + 1/v
What is linear magnification?
Linear magnification (m) is the ratio of the height of the image (h₁) to the height of the object (h₀). It’s also equal to the ratio of the image distance (v) to the object distance (u):
m = h₁/h₀ = v/u
What are some applications of lenses in optical instruments?
Lenses are used in many optical instruments:
Magnifying glass: A single convex lens used to magnify objects.
Compound microscope: Uses two convex lenses (objective and eyepiece) to produce a magnified image of a small object.
Telescope: Uses two convex lenses (objective and eyepiece) to magnify distant objects.
What are some applications of total internal reflection?
Total internal reflection has many applications:
Prism periscope: Used to see objects around corners.
Optical fiber: Used for transmitting light signals over long distances.
Cat’s eye reflectors: Used for safety in roads.
What are some applications of interference?
Interference of waves has many applications:
Anti-reflective coatings on lenses: Reduces glare by causing reflected light to interfere destructively.
Noise-canceling headphones: Use sound waves to interfere destructively with unwanted noise.
Holograms: Created using interference of light waves.
