Update Unit 3: Physics.md

Grade 10/Science/SNC2DZ/Unit 3: Physics.md

@@ -133,6 +133,43 @@
     - Where $`n_{1}`$ and $`n_{2}`$ are the refractive indexes of two different media
  - Snell's law: $`\dfrac{\sin\theta_2}{\sin\theta_1} = \dfrac{v_2}{v_1} = \dfrac{n_1}{n_2}`$
 
+## Thin Lens 
+- The optical center $`O`$ is the center of the lens.
+- The point where the light rays converge (extended or actual), is called the **Primary Focus** ($`F`$), and the focus that is on the opposite side of the primary focus
+is called the **Secondary Focus** ($`F^\prime`$).
+
+
+### Converging (double convex) lens
+- a lens that is thickest in the middle and that causes incident parallel light rays to converge through a single point after refraction
+- also called a bi-convex lens
+- the primary focus is on the right side of the lens, while the secondary focus is on the left side of the lens
+
+Some rules for converging lens for locating the image: (note that this only true for thin lenses, which are the only lenses in this unit?)
+
+1. A ray parrel to the principal axis is refracted through the principal/primary focus ($`F`$).
+2. A ray through the secondary principal focus ($`F^\prime`$) is refracted paarallel to the principal axis.
+3. A ray through the optical center $`O`$ continues straight without being refracted.
+
+|Location (Object) |Size|Attitude|Location (Image)|Type|
+|:-----------------|:---|:-------|:---------------|:---|
+|beyond $`2F^\prime`$|smaller|inverted|beteween $`2F`$ and $`F`$|real|
+|at $`2F^\prime`$|same size|inverted|at $`2F`$|real|
+|between $`2F^\prime`$ and $`F^\prime`$|larger|inverted|beyond $`2F`$|real|
+|at $`F^\prime`$|No clear image||||
+|inside $`F^\prime`$|larger|upright|same side as object (behind lens)| virtual|
+
+### Diverging (double concave) lens
+- a lens that is thinnest in the middle and that causes incident parallel light rays to spread aparet after refraction
+- also called a bi-concave lens
+- the primary focus is on the left side of the lens, while the secondary focus is on the right side of the lens
+
+Some rules for diverging lens for location the image: (note that this only true for thin lenses, which are the only lenses in this unit?)
+1. A ray parallel to the principal axis is refracted as if it had come through the principal focus ($`F`$)
+2. A ray that appears to pass through the secondary principal focus $`(F^\prime)`$ is refracter parallel to the principal axis
+3. A ray through the optical center ($`O`$) continues straight through on its path.
+
+A diverging lens **always** produces a `smaller`, `upright`, `virtual image` that is on the same side of the lens as the object.
+
 ## Total internal reflection
  - `Critical angle`: Angle of incidence that causes refracted ray to be perpendicular to normal
  - TIR occurs when angle of incidence exceeds critical angle, causing near-100% reflection
@@ -175,9 +212,38 @@ $`M = \frac{h_{i}}{h_{o}} = -\frac{d_{i}}{d_{o}}`$
  - `Lens`: Focuses light to form an **inverted real** image at the back of the eye
  - `Retina`: Captures **light** and converts it to **electrical signals**
  - `Optic nerve`: Transports information from the **retina** to the **brain** for processing
+ - `Cornea`: A protective layer on top of the lenses, refracts more light than the lenses, and focuses the light.
+ - `Accommodation`: The eye muscles streches/squishes the lens to change its shape inorder to focuse the image onto the retina. (changes the focal length)
 
 ### Focusing problems
  - `Myopia`: Near-sightedness
+    - The light rays converge before the retina, occurs when the distance between lens and the retina is too large or if the corena+lens combination coverges light too strongly
+    - light from distance objects is brought to a focus **infront** of the retina
+    - this can be fixed by using a diverging lens or a negative meniscus, the lens/meniscus diverge + refract the rays so that the light rays converge later on the retina
  - `Hyperopia`: Far-sightedness
+    - The light rays converge after the retina, occurs when the  distance between the lens and the retina is too little or if the corean+lens combaintion is too weak
+    - Light from nearby objects focuses **behind** the retina
+    - This can be fixed by using a converging lens or a positive meniscus, the lens/meniscus converge + refract the rays so they converge later on retina
  - `Presbyopia`: Far-sightedness due to aging
- - `Astigmatism`: Blurry vision for everything
+    - The eye looses its elasticity, and the **accommodation** mechanism does not work well. Can be fixed with a converging lens. 
+ - `Astigmatism`: Blurry vision for everything
+ - Contact lenses are basically glasses but on your eye (according to textbook), however they are ones that reshape your eye or reshape the lenses in your eyes.
+ - Laser eye surgery uses a laser to resphae the cornea of the eye in order to improve vision.
+
+## Applications Of Lenses
+- Not sure if its going to be tested, but put here in case:
+
+### Camera
+Basically it takes in objects that are far away (beyond 2F') and uses a converging mirror to focus it onto a film or digital sensor.
+
+### Movie Projector
+Basically it takes a small object (the film), places it between 2F' and F', then uses a converging mirror to make the image larger than object which is being projected onto the movie screen.
+
+### Magnifying Glass
+When an object is inside F' of the converging lens, the refracted light rays don't actually converge, but your brain extends these rays bacwards and produces an enlarged vritual image located on the same side of the lens as the object.
+
+### The Compound Microscope
+Uses 2 converging lens, the objective lens produces a real image inside F, and like the magnifying glass, the eyepiece lens refracts the real image, and then your brain extends the refracted rays from the eyepiece lens and see the larger virtual image.
+
+### The Refracting Teloscope
+Since light coming from far away are parallel, the light rays are beyond 2F', it uses 2 converging lens to do something similar to the compound microscope. What you actually see is the virtual image.