experiment 9: reflection and refraction of light Flashcards
speed at which light travels through a vacuum
c = 3.00 x 10^8 m/s.
or 300 000 km/s
where else can light travel
air
water
glass
* it slows down bcs it interacts with the atoms in those molecules
- atoms in the material absorbs, reemit and scatter the light
what happens when light strikes the interface between two transparent materials, such as water and air
the light generally divides into two parts
1. part of the light is reflected [reflected light]
2. other part is transmitted across the interface [transmitted light - may change direction as it enter the new material]
what happen when the incident ray does not strike the interface at normal incidence
the transmitted ray has a different direction than the incident ray.
[If light doesn’t hit the surface straight on (not at a 90° angle), it bends as it passes into the new material. This bending happens because light changes speed when it moves from one material to another.]
normal incidence
light hits a surface straight on, at a 90-degree angle to the surface
- light doesnt bend (refract) when it enters a new material
- continues in the same direction, although it may slow down or speed up depending on the material
It is when a ray enters the second material and changes direction
refracted
fraction, n2 and n1, of the two media.
Snell’s law of Refraction
The amount of bending depends on:
The angle at which the light hits the surface.
The refractive index of each material (how much it slows light down).
what is the formula of Snell’s Law
n1 sinθ1 = n2 sinθ2
n1 and n2: Refractive indices of the two materials.
θ1- angle of incidence
θ2 - angle of refraction
what are the materials that the lenses used in optical instruments, such as eyeglasses, cameras, and telescopes
transparent materials that refract light [converging lens - thicker in the middle than at the edges. It bends (refracts) light rays so they come together (converge) at a point called the focal point.]
- they refract the light in such a way that an image of the source of the
light is formed.
how does converging lens work
Every object gives off light rays in all directions.
When these rays pass through a converging lens, the lens bends them in such a way that they meet at one point on the other side. This creates an image of the object.
what can the ray-tracing method used to determine
location and size of the image
When tracing their paths, what are the following reasoning strategy for a converging lens.
Ray 1: Parallel to axis, then passes through far focal point.
- This ray initially travels parallel to the principal axis. In passing through a diverging lens, the ray is refracted away from the axis, and appears to have originated from the focal point on the left of the lens
Ray 2: Passes through near focal point, then parallel to axis.
- This ray leaves the object and moves toward the focal point on the right of the lens. Before reaching the focal point, however, the ray is refracted by the lens so as to exit parallel to the axis.
Ray 3: Passes unchanged through center of lens.
- This ray leaves the object and moves toward the focal point on the right of the lens. Before reaching
the focal point, however, the ray is refracted by the lens so as to exit parallel to the axis.
where do u place the light source
in ray box
how do u measure the angle
using a protractor
how far is the “the object”/ LED light source from a convex lens
75cm
with a 25cm (+200 mm) focal length
object distance:
image distance:
object distance:
btwn LED in holder and convex in holder
image distance:
btwn convex in holder and screen in holder
Lens equation
index card
Magnification eqn
index card
what are the reasoning strategy
focal length:
object distance:
image distance:
magnification:
focal length:
f + converging lens
f -diverging lens
object distance:
d0 + left of the lens (real object)
d0 - right of the lens (virtual object)
image distance:
di + image (real) formed to the right of the lens by a real object
di - image (virtual) formed to the left of the lens by a real object
magnification:
m + image that is upright w respect to the object
m - image that is inverted w respect to the object
